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Encyclopedia > Diamond simulants

This article addresses the many imitations of diamond. For a broader discussion of diamonds, see A scattering of round-brilliant cut diamonds shows off the many reflecting facets. The mineral diamond is a crystalline form, or allotrope, of carbon (other allotropes of carbon include graphite and coal). Diamonds are renowned for their superlative physical qualities, especially their hardness—the word diamond derives from the... diamond. For other uses of the word diamond, see Diamond has more than one meaning: Diamond is a mineral used in jewelry and tools. Diamonds is a card suit. In geometry, a diamond usually means a rhombus. Diamond Jubilee is a 60th anniversary. The Diamond Sutra is a Buddhist text. Diamond Comic Distributors holds the monopoly on wholesale distribution... diamond (disambiguation).

Photo of a round brilliant-cut cubic zirconia by Gregory Phillips. Taken in January 2004 and released under terms of the GNU FDL. File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. Click on date to download the file... Due to its low cost and close visual likeness to diamond, has remained the most gemologically and economically important diamond simulant since 1976.
Due to its low cost and close visual likeness to diamond, A round brilliant-cut cubic zirconia Cubic Zirconia (or CZ) is zirconium oxide (ZrO2), a mineral that is extremely rare in nature but is widely synthesized for use as a diamond simulant. The synthesized material is hard, optically flawless and usually colourless, but may be made in a variety of... cubic zirconia has remained the most gemologically and economically important diamond simulant since 1976.

The high price of A gemstone is a mineral, rock (as in lapis lazuli) or petrified material that when cut or faceted and polished is collectible or can be used in jewellery. Others are organic, such as amber (fossilised tree resin) and jet (a form of coal). Some beautiful gemstones are too soft or... gem-grade A scattering of round-brilliant cut diamonds shows off the many reflecting facets. The mineral diamond is a crystalline form, or allotrope, of carbon (other allotropes of carbon include graphite and coal). Diamonds are renowned for their superlative physical qualities, especially their hardness—the word diamond derives from the... diamonds has created a large demand for materials with similar Gemology (gemmology outside the United States) is the science, art and profession of identifying and evaluating gemstones. It may be considered a branch of mineralogy. Some jewelers are gemologists and as such are qualified to identify and appraise gems. There are professional schools and associations of gemologists and certification programs... gemological characteristics, known as diamond simulants or imitations. Simulants are distinct from Synthetic diamond is diamond produced through chemical or physical processes in a laboratory. Like naturally occurring diamond it is composed of a three-dimensional carbon crystal. Synthetic diamonds are also called cultured diamonds, manufactured diamonds, and artificial diamonds. History Synthetic diamonds were first produced on February 16, 1953 in Stockholm... synthetic diamond, which unlike simulants have This article addresses the material properties of diamond. For a broader discussion of diamonds, see diamond. For other uses of the word diamond, see diamond (disambiguation). Diamond is transparent to opaque, optically isotropic crystalline carbon. It is the hardest naturally-occurring material known—owing to its strong covalent bonding... material properties identical to those of natural diamond. This article addresses treatments designed to enhance the gemological characteristics of diamond. For a broader discussion of diamonds, see diamond. For other uses of the word diamond, see diamond (disambiguation). Diamond enhancements are specific treatments, performed on natural and sometimes synthetic diamonds (usually those already cut and polished into gems... Enhanced diamonds are also excluded from this definition. A diamond simulant may be artificial, natural, or in some cases a combination thereof. While their material properties depart markedly from those of diamond, simulants have certain desired characteristics—such as In optics, dispersion is a phenomenon that causes the separation of a wave into spectral components with different frequencies, due to a dependence of the waves speed on its frequency. It is most often described in light waves, though it may happen to any kind of wave that interacts... dispersion and In materials science, hardness is the characteristic of a solid material expressing its resistance to permament deformation. There are three principal operational definitions of hardness: Scratch hardness Indentation hardness Rebound, dynamic or absolute hardness Scratch hardness In mineralogy, hardness commonly refers to a materials ability to penetrate softer materials... hardness—which lend themselves to imitation. Trained gemologists with appropriate equipment are able to distinguish natural and synthetic diamonds from all diamond simulants, primarly by visual inspection.


The most common diamond simulants are high-leaded glass (i.e., A rhinestone is an imitation diamond made from rock crystal, glass or acrylic. Originally, rhinestones were rock crystals gathered from the river Rhine, but their availability was greatly increased when the French jeweller George Frederic Strass had the idea to coat the lower side of glass with metal powder around... rhinestones) and A round brilliant-cut cubic zirconia Cubic Zirconia (or CZ) is zirconium oxide (ZrO2), a mineral that is extremely rare in nature but is widely synthesized for use as a diamond simulant. The synthesized material is hard, optically flawless and usually colourless, but may be made in a variety of... cubic zirconia (CZ), both artificial materials. A number of other artificial materials, such as Strontium titanate (chemical symbol: SrTiO3) is a centrosymmetric non-ferroelectric material with a perovskite structure. Categories: Stub ... strontium titanate and synthetic Rutile is a mineral composed of titanium dioxide, TiO2, which occurs in three distinct forms, as: rutile, a tetragonal mineral usually of prismatic habit, often twinned; anatase or octahedrite, a tetragonal mineral of octahedral habit; and brookite, an orthorhombic mineral. Both octahedrite and brookite are relatively rare minerals. Rutilated quartz... rutile have been developed since the mid Events and trends Technology United States tests the first fusion bomb. See History of nuclear weapons Sputnik, the first man-made satellite, and thus the Sputnik crisis The De Havilland Comet enters service as the worlds first jet airliner Charles Townes builds a maser in 1953 at Columbia University... 1950s, but these are no longer in common use. Introduced at the end of the (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999... 20th century, the artificial product Moissanite was first found in 1893 as a small component of a meteorite in Arizona by Dr. Ferdinand Henri Moissan, after whom the material was named. Naturally occurring moissanite is exceedingly rare, having an appearance similar to that of diamond and a tetrahedral crystalline structure. In 1998 C3, Inc. (Charles... moissanite has gained popularity as a supposedly superior diamond simulant, although its much higher cost and limited production have kept it a relatively minor simulant.

Contents

Desired and differential properties

See also: This article addresses the material properties of diamond. For a broader discussion of diamonds, see diamond. For other uses of the word diamond, see diamond (disambiguation). Diamond is transparent to opaque, optically isotropic crystalline carbon. It is the hardest naturally-occurring material known—owing to its strong covalent bonding... Material properties of diamond


In order to be considered for use as a diamond simulant, a material must possess certain diamond-like properties. The most advanced artificial simulants have properties which closely approach diamond, but all simulants have one or more features that clearly and (for those familiar with diamond) easily differentiate them from diamond. To a gemologist, the most important of differential properties are those that foster non-destructive testing, and most of these are visual in nature. Non-destructive testing is preferred because most suspected diamonds are already cut into gemstones and set in Jewellery (spelled jewelry in American English) consists of ornamental devices worn by persons, typically made with gems and precious metals. Costume jewellery is made from less valuable materials. However, jewellery can and has been made out of almost every kind of material. Examples include bracelets, necklaces, rings, and earrings, as... jewelry, and if a destructive test (which mostly relies on the relative fragility and softness of non-diamonds) fails it may damage the simulant—this is not an acceptable outcome for most jewelry owners, as even if a stone is not a diamond it may still be of value.


Diamond and its simulants can be both compared and contrasted by the following properties:


Durability and density

The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. It was created by the German mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science. Mohs based the scale on ten readily... Mohs scale of mineral hardness is a non-linear scale of common Minerals are natural compounds formed through geological processes. The term mineral encompasses not only the materials chemical composition but also the mineral structures. Minerals range in composition from pure elements and simple salts to very complex silicates with thousands of known forms (organic compounds are usually excluded). The study... minerals' resistances to scratching. Diamond is at the top of this scale (hardness 10) as it is the In materials science, hardness is the characteristic of a solid material expressing its resistance to permament deformation. There are three principal operational definitions of hardness: Scratch hardness Indentation hardness Rebound, dynamic or absolute hardness Scratch hardness In mineralogy, hardness commonly refers to a materials ability to penetrate softer materials... hardest material known. Therefore a diamond can be scratched only by another diamond, so typically a diamond gemstone is free of scratches. Diamond's hardness also is visually evident (under the A microscope (Greek: micron = small and scopos = aim) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. The science of investigating small objects using such an instrument is called microscopy, and the term microscopic means minute or very small, not... microscope or loupe) by its highly For the file system called Lustre, see Lustre (file system) Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. For example, a diamond is said to have an adamantine lustre and pyrite is said to have a metallic... lustrous Facets are flat faces on geometric shapes. Gemstones commonly have facets cut into them as a way to improve their appearance. Of the many hundreds of facet arrangements that have been used, the most famous is probably the round brilliant cut, used for diamond. This arrangement of 57 facets was... facets (described as adamantine) which are perfectly flat, and its crisp, sharp facet edges. For a diamond simulant to be effective, it must be very hard relative to most gems. Most simulants fall far short of diamond's hardness, so they can be separated from diamond by their external flaws and poor polish.


In the recent past, the so-called "window pane test" was thought to be an assured method of identifying diamond. It is a potentially destructive test wherein a suspect diamond gemstone is scraped against a pane of glass, with a positive result being a scratch on the glass and none on the gemstone. The use of hardness points and scratch plates made of Corundum is the crystalline form of aluminium oxide and one of the rock-forming minerals. Corundum is naturally clear, but can have different colors when impurities are added. Transparent specimens are used as gems, called ruby if red, while all other colors are called sapphire. The word corundum comes from... corundum (hardness 9) are also used in place of glass. Hardness tests are inadvisable for three reasons: glass is fairly soft (typically 6 or below) and can be scratched by a large number of materials (including many simulants); diamond has four directions of perfect and easy In embryology, cleavage is the division of cells in the early embryo. The zygotes of many species undergo rapid cell cycles with no significant growth, producing a cluster of cells the same size as the original zygote. In mineralogy, the tendency of crystalline materials to split along definite planes, creating... cleavage (planes of structural weakness along which the diamond could split) which could be triggered by the testing process; and many diamond-like gemstones (including older simulants) are valuable in their own right.


The Relative density (also known as specific gravity) is a measure of the density of a material. It is dimensionless, equal to the density of the material divided by the density of water (or, sometimes used for gases, of air). Since waters density is 1.0 × 103 kg/m3 in... specific gravity (SG) or density of a gem diamond is fairly constant at 3.52. Most simulants are far above or slightly below this value, which can make them easy to identify if unset. High-density liquids such as di-iodomethane can be used for this purpose, but they are all highly For a list of biologically injurious substances, including toxins and other materials, as well as their effects, see poison. A toxin is a substance that causes injury to the health of a living thing on contact or absorption, typically by interacting with biological macromolecules such as enzymes and receptors. The... toxic so are usually avoided. A more practical method is to compare the expected size and For Carat as a unit of purity see Carat (purity) The carat is a unit of mass used for gems. The word derives from the Greek keration (fruit of the carob), via Arabic and Italian. In the past, different countries each had their own carat, roughly equivalent to a carob... carat weight of a suspect diamond to its measured parameters: for example, a A round brilliant-cut cubic zirconia Cubic Zirconia (or CZ) is zirconium oxide (ZrO2), a mineral that is extremely rare in nature but is widely synthesized for use as a diamond simulant. The synthesized material is hard, optically flawless and usually colourless, but may be made in a variety of... cubic zirconia (SG 5.6–6) will be 1.7 times the expected weight of an equivalently sized diamond.


Optics and color

Diamonds are usually cut into A scattering of brilliant cut diamonds shows off the many reflecting facets. Brilliant is one of the most used cuts for Diamonds. The brilliant cut was introduced in the middle of the seventeenth century. The first brilliants were known as Mazarins. They had 17 facets on the crown (upper half... brilliants to bring out their brilliance, the amount of light reflected back to the viewer, and fire, the degree of colorful See: Prism (geometry) Prism (optics) Prism (band) PRISM is an abbreviation for Probabilistic Symbolic Model Checker PRISM was an aborted RISC processor effort at DEC, see DEC PRISM This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. If an... prismatic flashes seen. Both properties are strongly affected by the cut of the stone, but they are a function of diamond's high The refractive index of a material is the factor by which electromagnetic radiation is slowed down (relative to vacuum) when it travels inside the material. For a non-magnetic material, the square of the refractive index is the materials dielectric constant (sometimes expressed as the relative permittivity multiplied by... refractive index (RI; the degree to which incident light is bent upon entering the stone) of 2.417 (as measured by sodium light, 589.3 nm) and high In optics, dispersion is a phenomenon that causes the separation of a wave into spectral components with different frequencies, due to a dependence of the waves speed on its frequency. It is most often described in light waves, though it may happen to any kind of wave that interacts... dispersion (the degree to which white light is split into its A spectral color is a color that is part of the optical spectrum. The spectral colors are: Red Orange Yellow Green Cyan Blue Violet (For historical reasons, it is common to exclude cyan.) Among some of the colors that are not spectral colors are: Grayscale colors, such as White, Silver... spectral colors within the stone) of 0.044, as measured by the sodium B and G line interval. Thus, if a diamond simulant's RI and dispersion are too low it will appear comparatively dull or "lifeless"; if the RI and dispersion are too high, the effect will be considered unreal or even tacky. Very few simulants have closely approximating RI and dispersion, but even the close simulants can be separated by an experienced observer. Direct measurements of RI and dispersion are impractical (a standard gemological refractometer has an upper limit of about RI 1.81), but several companies have devised In optics, reflectivity is the reflectance (the ratio of reflected power to incident power, generally expressed in decibels or percentage) at the surface of a material so thick that the reflectance does not change with increasing thickness; i.e., the intrinsic reflectance of the surface, irrespective of other parameters such... reflectivity meters to gauge a material's RI indirectly by measuring how well it reflects an Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. The name means below red (from the Latin infra, below), red being the color of visible light of longest... infrared beam.


Perhaps equally as important is optic character. Diamond and other In crystallography, the cubic crystal system is the most symmetric of the 7 crystal systems. The system is composed of the three Bravais lattices whose symmetry group is that of a cube. The three Bravais lattices that form the cubic crystal system are: The point groups that fall under this... cubic (and also An amorphous solid is a solid in which there is no long-range order of the positions of the atoms. (Solids in which there is long_range atomic order are called crystalline solids.) Most classes of solid materials can be found or prepared in an amorphous form. For instance, common window... amorphous) materials are Isotropic means independent of direction. Isotropic radiation has the same intensity regardless of the direction of measurement, and an isotropic field exerts the same action regardless of how the test particle is oriented. Isotropy is also a concept in mathematics. Some manifolds are isotropic, meaning that the geometry on the... isotropic, meaning light entering a stone behaves the same way regardless of direction. Conversely, most minerals are Anisotropic (meaning non-isotropic) is usually used to describe a directionally dependent phenomenon. For example, anisotropic radiation has different intensities in different directions, and an anisotropic field exerts different actions depending on how the test particle is oriented. Magnetic susceptibility or electrical conductivity, for example, can be anisotropic in certain... anisotropic which produces A calcite crystal laid upon a paper with some letters showing the double refraction Birefringence, or double refraction, is the division of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals, depending on... birefringence or double refraction of light entering the material in all directions other than an optic axis (a direction of single refraction in a doubly refractive material). Under low magnification, this birefringence is usually detectable as a visual doubling of a cut gemstone's rear facets or internal flaws. An effective diamond simulant should therefore be isotropic.


Under longwave (365 nm) Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. It can be subdivided into near UV (380–200 nm wavelength... ultraviolet light, diamond may Fluorescence induced by exposure to ultraviolet light in vials containing various sized cadmium selenide (CdSe) quantum dots. Fluorescence is a luminescence, i.e. optical phenomenon in cold bodies, in which a molecule absorbs a high-energy photon, and re-emits it as a lower-energy (longer-wavelength) photon. The energy... fluoresces a blue, yellow, green, mauve, or red of varying intensity. The most common fluorescence is blue, and such stones may also Phosphorescence is a radiative transition involving a change in the spin multiplicity of a molecule. Because of this change, the radiative transition is delayed, and the phosphorescent material glows a while after the incident illumination stops. Because of this, phosphorescent materials are most commonly called glow-in-the-dark. In... phosphoresce yellow—this is thought to be a unique combination among gemstones. There is usually little if any response to shortwave ultraviolet, in contrast to many diamond simulants. Similarly, because most diamond simulants are artificial they tend to have uniform properties: in a multi-stone diamond ring, one would expect the individual diamonds to fluoresce differently (in different colors and intensities, with some likely to be inert). If all the stones fluoresce in an identical manner, they are unlikely to be diamond.


Most "colorless" diamonds are actually tinted yellow or brown to some degree, whereas artificial simulants are usually completely colorless—the equivalent of a perfect "D" in Jewelers set diamonds in groups of similar colors. A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. However, in reality almost no gem-sized natural diamonds are absolutely perfect. The color of a diamond may be affected by chemical impurities and/or structural defects... diamond color terminology. This "too good to be true" factor is important to consider; colored diamond simulants meant to imitate fancy diamonds are more difficult to spot in this regard, but the simulants' colors rarely approximate. In most diamonds (even colorless ones) a characteristic An absorption spectrum is a diagram depicting the wavelengths of electromagnetic radiation absorbed by a material, usually a gas. It can be regarded as the opposite to an emission spectrum, which is a depiction of the specific wavelengths emitted by a material. Let us consider white light, which consists of... absorption spectrum can be seen (via a direct-vision This article or section should be merged with Spectrometer, Spectrograph A spectroscope is a device which measures the spectrum of light. Early spectroscopes were simply a prism with graduations marking wavelengths. Modern spectroscopes generally use a diffraction grating, a movable slit and some kind of photodetector, all automated and controlled... spectroscope), consisting of a fine line at 415 nm. The A dopant is an impurity that is added in small amounts to a pure substance to change its properties. Examples Boron, arsenic, and antimony, among other substances, are used as dopants when added to a pure semiconductor material to alter its electrical characteristics. Artificially produced gemstones (such as rubies) sometimes... dopants used to impart color in artificial simulants may be detectable as a complex A rare earth is an oxide of a rare earth element. Often rare earth elements themselves are loosely called rare earths. Rare earth elements, or metals, are the lanthanides and actinides. They come from the f-block. They are: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium... rare earth absorption spectrum, which is never seen in diamond.


Also present in most diamonds are certain internal and external flaws or inclusions, the most common of which are fractures and solid foreign crystals. Artificial simulants are usually internally flawless, and any flaws that are present are characteristic of the manufacturing process. The inclusions seen in natural simulants will often be unlike those ever seen in diamond, most notably A liquid will assume the shape of its container. One of the four phases of matter, a liquid is a fluid whose volume is fixed under conditions of constant temperature and pressure; and, whose shape is usually determined by the container it fills. Furthermore, liquids exert pressure on the sides... liquid "feather" inclusions. The Diamond Cutting is the art, skill and, increasingly, science of changing a diamond from a rough stone into an attractive gem. It is possible only because the hardness of diamond varies widely according to the direction one is trying to cut or grind. Cut has two meanings in relation to... diamond cutting process will often leave portions of the original crystal's surface intact. These are termed naturals and are usually on the girdle of the stone; they take the form of triangular, rectangular, or square pits (etch marks) and are seen only in diamond.


Thermal and electrical

Diamond is an extremely effective In physics, thermal conductivity, λ, is the quantity of heat transmitted, due to unit temperature gradient, in unit time under steady conditions in a direction normal to a surface of unit area, when the heat transfer is dependent only on the temperature gradient thermal conductivity = heat flow rate / (distance × temperature... thermal conductor and usually an The article on electrical energy is located elsewhere. Electricity is a property of certain subatomic particles (e.g. electrons / protons) which couples to electromagnetic fields and causes attractive and repulsive forces between them. Electricity gives rise to one of the four fundamental forces of nature, and is a conserved property... electrical Insulators are materials which prevent the flow of heat (thermal insulators) or electric charge (electrical insulators). The opposite of electrical insulators are conductors and semiconductors, which permit the flow of charge (Note: a semiconductor is strictly speaking also an insulator, since it prevents the flow of electric charge at low... insulator. The former property is widely exploited in the use of an electronic thermal probe to separate diamonds from their imitations. These probes consist of a pair of battery-powered A thermistor is a type of resistor used to measure temperature changes, relying on the change in its resistance with changing temperature. If we assume that the relationship between resistance and temperature is linear (i.e. we make a first-order approximation), then we can say that: where = change in... thermistors mounted in a fine Copper is also the title of a web and print comic: see Copper (comic). General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11 , 4, d Density, Hardness 8920 kg/m3, 3.0 Appearance copper, metallic Atomic properties Atomic weight 63.546 amu Atomic radius... copper tip. One thermistor functions as a Heat (abbreviated Q, also called heat change) is the transfer of thermal energy between two bodies which are at different temperatures. The SI unit for heat is the joule. The relationship between heat and energy is similar to that between work and energy. Heat flows between regions that are not... heating device while the other measures the temperature of the copper tip: if the stone being tested is a diamond, it will conduct the tip's thermal energy rapidly enough to produce a measurable temperature drop. As most simulants are thermal insulators, the thermistor's heat will not be conducted. This test takes about 2–3 seconds. The only possible exception is Moissanite was first found in 1893 as a small component of a meteorite in Arizona by Dr. Ferdinand Henri Moissan, after whom the material was named. Naturally occurring moissanite is exceedingly rare, having an appearance similar to that of diamond and a tetrahedral crystalline structure. In 1998 C3, Inc. (Charles... moissanite, which has a thermal conductivity similar to diamond: older probes can be fooled by moissanite, but newer testers are sophisticated enough to differentiate the two materials.


A diamond's electrical conductance is only relevant to blue or gray-blue stones, because the interstitial General Name, Symbol, Number Boron, B, 5 Series Metalloids Group, Period, Block 13 (IIIA), 2, p Density, Hardness 2460 kg/m3, 9.3 Appearance Black Atomic properties Atomic weight 10.811 amu Atomic radius (calc.) 85 (87) pm Covalent radius 82 pm van der Waals radius no data Electron configuration... boron responsible for their color also makes them A semiconductor is a material that is an insulator at very low temperature, but which has a sizable electrical conductivity at room temperature. The distinction between a semiconductor and an insulator is not very well-defined, but roughly, a semiconductor is an insulator with a band gap small enough that... semiconductors. Thus a suspected blue diamond can be affirmed if it completes an An electrical network or electrical circuit is an interconnection of analog electrical elements such as resistors, inductors, capacitors, diodes, switches and transistors. It can be as small as an integrated circuit on a silicon chip, or as large as an electricity distribution network. A circuit is a network that has... electric circuit successfully.


Artificial simulants

Diamond has been imitated by artificial materials for hundreds of years: advances in technology have seen the development of increasingly better simulants with properties ever nearer those of diamond. Although most of these simulants were characteristic of a certain time period, their large production volumes ensured that all continue to be encountered with varying frequency in jewelry of the present. Nearly all were first conceived for intended use in High tech refers to high technology, technology that is at the cutting-edge and the most advanced currently available. The adjective form is hyphenated: high-tech. Because the high-tech sector of the economy develops or uses the most advanced technology known, it is often seen as having the most... high technology, such as A laser system generally consists of three important parts: An energy source (usually referred to as the pump or pump source); A gain medium or laser medium; A mirror, or system of mirrors, forming an optical resonator. Schematic diagram of a typical laser, showing the three major parts The pump... lasing mediums, A varistor is a type of resistor with a significantly non-ohmic current-voltage characteristic. The name is a portmanteau of variable resistor*, which is misleading since it is not continuously user-variable like a potentiometer or rheostat, and is not a resistor but in fact a capacitor. Varistors are... varistors, and Intel bubble memory module Bubble memory is a type of computer memory that uses a thin film of a magnetic material to hold small magnetized areas, known as bubbles, which each store one bit of data. Bubble memory was a very promising technology in the 1970s, but flopped commercially when... bubble memory. Due to their limited present supply, collectors may pay a premium for the older types.


Summary table

Diamond Simulants and Their Gemological Properties
Material Formula The refractive index of a material is the factor by which electromagnetic radiation is slowed down (relative to vacuum) when it travels inside the material. For a non-magnetic material, the square of the refractive index is the materials dielectric constant (sometimes expressed as the relative permittivity multiplied by... Refractive
index(es)

589.3 nm
In optics, dispersion is a phenomenon that causes the separation of a wave into spectral components with different frequencies, due to a dependence of the waves speed on its frequency. It is most often described in light waves, though it may happen to any kind of wave that interacts... Dispersion
431 - 687 nm
In materials science, hardness is the characteristic of a solid material expressing its resistance to permament deformation. There are three principal operational definitions of hardness: Scratch hardness Indentation hardness Rebound, dynamic or absolute hardness Scratch hardness In mineralogy, hardness commonly refers to a materials ability to penetrate softer materials... Hardness
( Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. It was created by the German mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science. Mohs based the scale on ten readily... Mohs'
scale
)
Relative density (also known as specific gravity) is a measure of the density of a material. It is dimensionless, equal to the density of the material divided by the density of water (or, sometimes used for gases, of air). Since waters density is 1.0 × 103 kg/m3 in... Density
(g/cm3)
In physics, thermal conductivity, λ, is the quantity of heat transmitted, due to unit temperature gradient, in unit time under steady conditions in a direction normal to a surface of unit area, when the heat transfer is dependent only on the temperature gradient thermal conductivity = heat flow rate / (distance × temperature... Thermal
Cond.
State of
the art
A scattering of round-brilliant cut diamonds shows off the many reflecting facets. The mineral diamond is a crystalline form, or allotrope, of carbon (other allotropes of carbon include graphite and coal). Diamonds are renowned for their superlative physical qualities, especially their hardness—the word diamond derives from the... Diamond C 2.417 0.044 10 3.52 Excellent 1476 –

Artificial Simulants:
For eyeglasses, see spectacles. For the drinking vessel, see glass (drinkware). The physics definition of a glass is a uniform amorphous solid material, usually produced when a suitably viscous molten material cools very rapidly, thereby not giving enough time for a regular crystal lattice to form. A simple example is... Glasses The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. It is found in nature in several forms, including quartz and opal. In fact, silica has 17 crystalline forms. Also, horsetail is one of the plants which is rich in Silica. It is... Silica with
For the lead in news writing, see news style. For the lead in acting, see leading actor. General Name, Symbol, Number Lead, Pb, 82 Chemical series Poor metals Group, Period, Block 14(IVA), 6 , p Density, Hardness 11340 kg/m3, 1.5 Appearance bluish white Atomic properties Atomic weight Note... Pb, General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13 (IIIA), 3, p Density, Hardness 2700 kg/m3, 2.75 Appearance silvery Atomic properties Atomic weight 26.981538 amu Atomic radius (calc.) 125 pm (118 pm) Covalent radius 118 pm van der Waals radius no... Al, &/or General Name, Symbol, Number Thallium, Tl, 81 Chemical series Poor metals Group, Period, Block 13 (IIIA), 6 , p Density, Hardness 11.85 Mg/m³, 1.2 Appearance Silvery white Atomic properties Atomic weight 204.3833 g/mol Atomic radius (calc.) 190 (156) pm Covalent radius 148 pm van der Waals... Tl
~ 1.6 > 0.020 < 6 2.4 – 4.2 Poor 1700 –
White
Sapphire is the single crystal form of aluminium oxide (Al2O3). It can be found naturally as gemstones or manufactured in large crystal boules for a variety of applications. Sapphire Gems Sapphire is any gemstone-quality corundum. (The red variety of corundum is also known as ruby.) When color is not... Sapphire
Al2O3 1.762 – 1.770 0.018 9 3.97 Poor 1900 – 1947
Spinel is one of a group of minerals which crystallize in the isometric system with an octahedral habit, and whose chemical compositions are analogous. These minerals are combinations of bivalent and trivalent oxides of magnesium, zinc, iron, manganese, aluminium and chromium, the general formula being represented as RO·R... Spinel MgO·Al2O3 1.727 0.020 8 ~ 3.6 Poor 1920 – 1947
Rutile is a mineral composed of titanium dioxide, TiO2, which occurs in three distinct forms, as: rutile, a tetragonal mineral usually of prismatic habit, often twinned; anatase or octahedrite, a tetragonal mineral of octahedral habit; and brookite, an orthorhombic mineral. Both octahedrite and brookite are relatively rare minerals. Rutilated quartz... Rutile TiO2  ? – 2.8 0.33 ~ 6 4.25 Poor 1947 – 1955
Strontium titanate (chemical symbol: SrTiO3) is a centrosymmetric non-ferroelectric material with a perovskite structure. Categories: Stub ... Strontium
Titanate
SrTiO3 2.41 0.19 5.5 5.13 Poor 1955 – 1970
YAG Y3Al5O12 1.83 0.028 8.25 4.55 – 4.65 Poor 1970 – 1975
GGG Gd3Ga5O12 1.97 0.045 7 7.02 Poor 1973 – 1975
A round brilliant-cut cubic zirconia Cubic Zirconia (or CZ) is zirconium oxide (ZrO2), a mineral that is extremely rare in nature but is widely synthesized for use as a diamond simulant. The synthesized material is hard, optically flawless and usually colourless, but may be made in a variety of... Cubic
Zirconium
ZrO2(+
rare earths)
~ 2.2 ~ 0.06 ~ 8.3 ~ 5.7 Poor 1976 –
Moissanite was first found in 1893 as a small component of a meteorite in Arizona by Dr. Ferdinand Henri Moissan, after whom the material was named. Naturally occurring moissanite is exceedingly rare, having an appearance similar to that of diamond and a tetrahedral crystalline structure. In 1998 C3, Inc. (Charles... Moissanite SiC 2.648 – 2.691 0.104 9.25 3.2 High 1998 –

The "refractive index(es)" column shows one refractive index for singly refractive substances, and a range for doubly refractive substances.


1700 onwards

The formulation of For eyeglasses, see spectacles. For the drinking vessel, see glass (drinkware). The physics definition of a glass is a uniform amorphous solid material, usually produced when a suitably viscous molten material cools very rapidly, thereby not giving enough time for a regular crystal lattice to form. A simple example is... glasses using For the lead in news writing, see news style. For the lead in acting, see leading actor. General Name, Symbol, Number Lead, Pb, 82 Chemical series Poor metals Group, Period, Block 14(IVA), 6 , p Density, Hardness 11340 kg/m3, 1.5 Appearance bluish white Atomic properties Atomic weight Note... lead, Aluminium oxide (or aluminum oxide) (Al2O3) is a chemical compound of aluminium and oxygen. It is also referred to as alumina for short, a name commonly used in the mining, ceramic and materials science communities. Aluminium oxide is the main component of bauxite, the principal ore of aluminium. Industrially, bauxite... alumina, and General Name, Symbol, Number Thallium, Tl, 81 Chemical series Poor metals Group, Period, Block 13 (IIIA), 6 , p Density, Hardness 11.85 Mg/m³, 1.2 Appearance Silvery white Atomic properties Atomic weight 204.3833 g/mol Atomic radius (calc.) 190 (156) pm Covalent radius 148 pm van der Waals... thallium to increase RI and dispersion began in the late Adoration, by Peter Paul Rubens: dynamic figures spiral down around a void: draperies blow: a whirl of movement lit in a shaft of light, rendered in a free bravura handling of paint The Baroque was a style in art that used exaggerated motion and clear, easily interpreted detail to produce... Baroque period. These glasses are fashioned into A scattering of brilliant cut diamonds shows off the many reflecting facets. Brilliant is one of the most used cuts for Diamonds. The brilliant cut was introduced in the middle of the seventeenth century. The first brilliants were known as Mazarins. They had 17 facets on the crown (upper half... brilliants, and when freshly cut they can be surprisingly effective diamond simulants. Known as rhinestones, pastes, or strass, glass simulants are a common feature of Antique can stand for any of several things: An antique is an object, often furniture or any other domestic item, that is highly valued because of its age, or because it belongs to a specific time period. Antique is a province of the Philippines. Antique is a musical duo from... antique Jewellery (spelled jewelry in American English) consists of ornamental devices worn by persons, typically made with gems and precious metals. Costume jewellery is made from less valuable materials. However, jewellery can and has been made out of almost every kind of material. Examples include bracelets, necklaces, rings, and earrings, as... jewelry, and in such cases rhinestones can be valuable historical artifacts in their own right. The great softness (below hardnes 6) imparted by the lead means a rhinestone's facet edges and faces will quickly become rounded and scratched. Together with A conchoidal fracture is produced when some types of mineral, such as obsidian and flint, are broken. The fracture takes the form of a curved surface, reminiscent of the interior of a shell. This characteristic meant that these minerals were widely used in the stone age to make sharp tools... conchoidal fractures, and air bubbles or flow lines within the stone, these features make glass imitations easy to spot under only moderate magnification. In contemporary production it is more common for glass to be molded rather than cut into shape: in these stones the facets will be concave and facet edges rounded, and mold marks or seams may also be present. Glass has also been combined with other materials to produce composites.


1900–1947

The first This article is about the form of solid matter. For other uses of this word, see Crystal (disambiguation). Insulin crystals A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. Generally, fluid substances... crystalline artificial diamond simulants were synthetic white Sapphire is the single crystal form of aluminium oxide (Al2O3). It can be found naturally as gemstones or manufactured in large crystal boules for a variety of applications. Sapphire Gems Sapphire is any gemstone-quality corundum. (The red variety of corundum is also known as ruby.) When color is not... sapphire ( General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13 (IIIA), 3, p Density, Hardness 2700 kg/m3, 2.75 Appearance silvery Atomic properties Atomic weight 26.981538 amu Atomic radius (calc.) 125 pm (118 pm) Covalent radius 118 pm van der Waals radius no... Al2O3, pure Corundum is the crystalline form of aluminium oxide and one of the rock-forming minerals. Corundum is naturally clear, but can have different colors when impurities are added. Transparent specimens are used as gems, called ruby if red, while all other colors are called sapphire. The word corundum comes from... corundum) and Spinel is one of a group of minerals which crystallize in the isometric system with an octahedral habit, and whose chemical compositions are analogous. These minerals are combinations of bivalent and trivalent oxides of magnesium, zinc, iron, manganese, aluminium and chromium, the general formula being represented as RO·R... spinel (MgO·Al2O3, pure General Name, Symbol, Number magnesium, Mg, 12 Series alkaline earth metals Group, Period, Block 2 (IIA), 3, s Density, Hardness 1738 kg/m³, 2.5 Appearance silvery white Atomic properties Atomic weight 24.305 amu Atomic radius (calc.) 150 pm (145 pm) Covalent radius 130 pm van der Waals radius... magnesium aluminium An oxide is a chemical compound of oxygen with other chemical elements, e.g. rust ( iron oxide) or bauxite ( aluminium oxide), usually created through the process of oxidation. Oxides are extremely common in Earths crust, and indeed in solid matter throughout the universe. Oxides can be named by how... oxide). Both have been synthesized in large quantities since the first decade of the (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999... 20th century via the Verneuil or flame-fusion process, although spinel was not in wide use until the Centuries: 19th century - 20th century - 21st century Decades: 1870s 1880s 1890s 1900s 1910s - 1920s - 1930s 1940s 1950s 1960s 1970s Years: 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 Referred to as the Roaring 20s. Events and trends Technology John Logie Baird invents the first working television system... 1920s. The Verneuil process involves an inverted oxy- General Name, Symbol, Number Hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1 (IA), 1 , s Density, Hardness 0.0899 kg/m3, NA Appearance colorless Atomic properties Atomic weight 1.00794 amu Atomic radius (calc) 25 (53) pm Covalent radius 37 pm van der Waals radius 120 pm Electron... hydrogen A blowgun or blowpipe is a simple weapon consisting of a small tube for firing light projectiles, or darts. The wielder blows into one end, forcing the dart out the other. Often, for increased effectiveness, the dart is tipped with a poison, most famously curare. Many cultures have used this... blowpipe, with purified feed powder mixed with General Name, Symbol, Number Oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16 (VIA), 2, p Density, Hardness 1.429 kg/m3, NA Appearance colorless Atomic properties Atomic weight 15.9994 g/mol Atomic radius (calc.) 60 (48) pm Covalent radius 73 pm van der Waals radius 152 pm... oxygen that is carefully fed through the blowpipe. The feed powder falls through the oxy-hydrogen flame, melts, and lands on a rotating and slowly descending pedestal below. The height of the pedestal is constantly adjusted to keep its top at the optimal position below the flame, and over a number of hours the molten powder cools and crystallizes to form a single pedunculated pear or A boule is a term used to describe a single crystal ingot produced by synthetic means. In the semiconductor industry they can be mades by a number of methods, such as the Bridgeman technique, or Czochralski process. A long, usually circular rod is produced. A semiconductor crystal boule is normally... boule crystal. The process is an economical one, with crystals of up to 9 centimeters (3.5 inches) in diameter grown. Boules grown via the modern The Czochralski process is a method of crystal growth used to obtain single crystals of semiconductors, metals (e.g. palladium, platinum, silver, gold) and salts. The most important application may be the growth of large cylindrical ingots, or boules, of single-crystal silicon. High-purity, semiconductor-grade silicon (only a... Czochralski process may weigh several kilograms.


Synthetic sapphire and spinel are durable materials (hardness 9 and 8) that take a good polish, but due to their much lower RI when compared to diamond (1.762–1.770 for sapphire, 1.727 for spinel) they are "lifeless" when cut. (Synthetic sapphire is also anisotropic, making it even easier to spot.) Their low RIs also mean a much lower dispersion (0.018 and 0.020), so even when cut into brilliants they lack the fire of diamond. Nevertheless synthetic spinel and sapphire were popular diamond simulants from the 1920s up until the late Centuries: 19th century - 20th century - 21st century Decades: 1890s 1900s 1910s 1920s 1930s - 1940s - 1950s 1960s 1970s 1980s 1990s Years: 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 Events and trends Technology First nuclear bomb First cruise missile, the V1 flying bomb and the first ballistic missile, the... 1940s, when newer and better simulants began to appear. Both have also been combined with other materials to create composites. Commercial names once used for synthetic sapphire include Diamondette, Diamondite, Jourado Diamond', and Thrilliant. Names for synthetic spinel included Corundolite, Lustergem, Magalux, and Radient.


1947–1970

The first of the optically "improved" simulants was synthetic Rutile is a mineral composed of titanium dioxide, TiO2, which occurs in three distinct forms, as: rutile, a tetragonal mineral usually of prismatic habit, often twinned; anatase or octahedrite, a tetragonal mineral of octahedral habit; and brookite, an orthorhombic mineral. Both octahedrite and brookite are relatively rare minerals. Rutilated quartz... rutile (TiO2, pure General Name, Symbol, Number Titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Density, Hardness 4507 kg/m3, 6 Appearance Silvery metallic Atomic properties Atomic weight 47.867 amu Atomic radius (calc.) 140 (176) pm Covalent radius 136 pm van der Waals radius no data Electron... titanium oxide). Introduced in 1947 was a common year starting on Wednesday (link will take you to calendar). Events January January 1 - British mines nationalized January 1 - Nigeria gains limited autonomy January 1 - The Canadian Citizenship Act went into effect January 3 - Proceedings of the U.S. Congress are televised for the first time... 1947 1948 is a leap year starting on Thursday (link will take you to calendar). Events January-February January 1 - Nationalisation of UK railways to form British Railways. Arab militants lay siege to the Jewish Quarter of the Old City of Jerusalem. First day of the Italian republican constitution. January 4... 48, synthetic rutile possesses plenty of life when cut—perhaps too much life for a diamond simulant. Synthetic rutile's RI and dispersion (2.8 and 0.33) are so much higher than diamond that the resultant brilliants look almost The mineraloid opal is amorphous SiO2·nH2O; hydrated silicon dioxide, the water content sometimes being as high as 20%. Opal ranges from colorless through white, milky blue, gray, red, yellow, green, brown and black. Often many of these colors can be seen at once, caused by interference and diffraction of... opal-like in their display of prismatic colors. Synthetic rutile is also doubly refractive: although some stones are cut with the table perpendicular to the optic axis to hide this property, merely tilting the stone will reveal the doubled back facets.


The continued success of synthetic rutile was also hampered by the material's inescapable yellow tint, which producers were never able to remedy. However, synthetic rutile in a range of different colors, including blues and reds, were produced using various metal oxide A dopant is an impurity that is added in small amounts to a pure substance to change its properties. Examples Boron, arsenic, and antimony, among other substances, are used as dopants when added to a pure semiconductor material to alter its electrical characteristics. Artificially produced gemstones (such as rubies) sometimes... dopants. These and the near-white stones were extremely popular if unreal stones. Synthetic rutile is also fairly soft (hardness ~6) and brittle, and therefore wears poorly. It is synthesized via a modification of the Verneuil process, which uses a third oxygen pipe to create a tricone burner—this is necessary to produce a single crystal, due to the much higher oxygen losses involved in the oxidation of titanium. The technique was invented by Charles H. Moore, Jr. at the South Amboy is a city located in Middlesex County, New Jersey. As of the 2000 census, the city had a total population of 7,913. South Amboy is governed under the Faulkner Act (Mayor-Council) system of municipal government. Geography South Amboy is located at 40°2853 North, 74... South Amboy, State nickname: The Garden State Other U.S. States Capital Trenton Largest city Newark Governor Richard Codey Official languages None defined Area 22,608 km² (47th)  - Land 19,231 km²  - Water 3,378 km² (14.9%) Population (2000)  - Population 8,414,350 (9th)  - Density... New Jersey-based National Lead Company (later N. L. Industries). National Lead and Union Carbide is a chemical manufacturer, now a subsidiary of The Dow Chemical Company. The company is most well-known for the Bhopal Disaster in 1984, in which the leakage of the highly toxic gas methyl isocyanate (MIC) killed thousands in Bhopal, India. The chairman Warren Anderson was charged with... Union Carbide were the primary producers of synthetic rutile, and peak annual production reached 750,000 carats (150 kg or 330 pounds). Some of the many commercial names applied to synthetic rutile include: Astryl, Diamothyst, Gava or Java Gem, Meredith, Miridis, Rainbow Diamond, Rainbow Magic Diamond, Rutania, Titangem, Titania, and Ultamite.


National Lead was also where research into the synthesis of another titanium compound, Strontium titanate (chemical symbol: SrTiO3) is a centrosymmetric non-ferroelectric material with a perovskite structure. Categories: Stub ... strontium titanate ( General Name, Symbol, Number Strontium, Sr, 38 Series Alkaline earth metal Group, Period, Block 2 (IIA), 5, s Density, Hardness 2630 kg/m3, 1.5 Appearance silvery white metallic Atomic properties Atomic weight 87.62 amu Atomic radius 215.1 pm Covalent radius 192 pm van der Waals radius no... SrTiO3, pure tausonite), was conducted. Research was done during the late 1940s and early Events and trends Technology United States tests the first fusion bomb. See History of nuclear weapons Sputnik, the first man-made satellite, and thus the Sputnik crisis The De Havilland Comet enters service as the worlds first jet airliner Charles Townes builds a maser in 1953 at Columbia University... 1950s by Leon Merker and Langtry E. Lynd, who also used a tricone modification of the Verneuil process. Upon its commercial introduction in 1955 is a common year starting on Saturday. Events January-April January 2 - Panama president Jose Antonio Remon is assassinated. January 19 - The Scrabble board game debuts. February 8 - Nikolai Bulganin ousts Georgi Malenkov February 13 - Israel obtains 4 of the 7 Dead Sea scrolls. February 23 - First meeting of... 1955, strontium titanate quickly replaced synthetic rutile as the most popular diamond simulant. This was due not only to strontium titanate's novelty, but to its superior optics: its RI (2.41) is very close to that of diamond, while its dispersion (0.19), although also very high, was a significant improvement over synthetic rutile's psychedelic display. Perhaps most importantly was the complete lack of yellow tint that so plagued synthetic rutile. Dopants were also used to give synthetic titanate a variety of colors, including yellow, orange to red, blue, and black. The material is also Isotropic means independent of direction. Isotropic radiation has the same intensity regardless of the direction of measurement, and an isotropic field exerts the same action regardless of how the test particle is oriented. Isotropy is also a concept in mathematics. Some manifolds are isotropic, meaning that the geometry on the... isotropic like diamond, meaning there is no distracting doubling of facets as seen in synthetic rutile.


Strontium titanate's only major drawback (if one excludes excess fire) is fragility. It is both softer (hardness 5.5) and more brittle than synthetic rutile—for this reason, strontium titanate was also combined with more durable materials to create composites. It was otherwise the best simulant around at the time, and at its peak annual production was 1.5 million carats (300 kg or 660 pounds). Due to A patent is a set of exclusive rights granted by a government to an inventor or applicant for a limited amount of time (normally maximum 20 years from the filing date, depending on extension). The term patent originates from the latin word patere which means to lay open (to public... patent coverage all The United States of America — also referred to as the United States, the U.S.A., the U.S., America¹, the States, or (archaically) Columbia — is a federal republic of 50 states located primarily in central North America (with the exception of two states: Alaska and Hawaii... US production was by National Lead, while large amounts were produced overseas by Nakazumi Company of Official language Japanese Capital Tokyo Largest City Tokyo Emperor Akihito Prime Minister Junichiro Koizumi Area  - Total  - % water Ranked 60th 377,835 km² 0.8% Population  - Total ( 2004)  - Density Ranked 10th 127,333,002 337/km² GDP  - Total (PPP, 2005)  - Total (nominal)  ... Japan. Commercial names for strontium titanate included Brilliante, Diagem, Diamontina, Fabulite, and Marvelite.


1970–1976

From about 1970 was a common year starting on Thursday. Events January-February January 1 - Construction begins on Arcosanti, by Paolo Soleri, in Mayer, Arizona, located 65, miles north of Phoenix, Arizona. January 1 - Unix epoch at 00:00:00 UTC. January 12 - Biafra capitulates, ending the Nigerian civil war. January 15... 1970 strontium titanate began to be replaced by a new class of diamond imitations: the "synthetic The Garnet group of minerals show crystals with a habit of dodecahedrons and trapezohedrons. They are nesosilicates with the same general formula, A3B2(SiO4)3. Many different chemical elements are included in the several varieties of garnet, including calcium, magnesium, aluminium, iron2+, iron3+, chromium, manganese, and titanium. Garnets show no... garnets." These are not true garnets in the usual sense because they are An oxide is a chemical compound of oxygen with other chemical elements, e.g. rust ( iron oxide) or bauxite ( aluminium oxide), usually created through the process of oxidation. Oxides are extremely common in Earths crust, and indeed in solid matter throughout the universe. Oxides can be named by how... oxides rather than In chemistry, a silicate is a compound consisting of silicon and oxygen (SixOy), one or more metals, and possibly hydrogen. It is also used to denote the salts of silica or of one of the silicic acids. Silicate minerals are noted for their tetrahedral form. Sometimes the tetrahedra are joined... silicates, but they do share natural garnet's In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. A crystal structure is composed of a unit cell, a set of atoms arranged in a particular way, which is periodically repeated in three dimensions on a lattice. The spacings between unit cells in... crystal structure (both are cubic and therefore isotropic) and the general formula A3B2C3O12. While in natural garnets C is always General Name, Symbol, Number silicon, Si, 14 Series metalloid Group, Period, Block 14 (IVA), 3, p Density, Hardness 2330 kg/m3, 6.5 Appearance dark grey, bluish tinge Atomic properties Atomic weight 28.0855 amu Atomic radius (calc.) 110 pm (111 pm) Covalent radius 111 pm van der Waals radius... silicon and A and B may be one of several common Generally, an element is a basic part that is the foundation of something. For a long time, elements (classical element) were believed (by the Pythagoreans and alchemists for example) to be the building blocks of all matter in the universe. Similarly, Chinese Taoism holds that the universe is based around... elements, most synthetic garnets are composed of uncommon de;Metalle der Seltenen Erden Categories: Stub | Chemical element groups ... rare earth elements. They are the only diamond simulants (aside from rhinestones) with no known natural counterparts: gemologically they are best termed artificial rather than synthetic, because the latter term is reserved for human-made materials that can also be found in nature.


Although a number of artificial garnets were successfully grown, only two became important as diamond simulants. The first was yttrium aluminium garnet (YAG; Y3Al5O12) in the late Centuries: 19th century - 20th century - 21st century Decades: 1900s 1910s 1920s 1930s 1940s 1950s - 1960s - 1970s 1980s 1990s 2000s 2010s Years: 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 Events and trends The 1960s was a turbulent decade of change around the world. Many of the trends of... 1960s. It was (and still is) produced via the Czochralski or crystal-pulling process, which involves growth from the melt. An Alternate meaning: Iridium (satellite) General Name, Symbol, Number Iridium, Ir, 77 Chemical series transition metals Group, Period, Block 9, 6, d Density, Hardness 22650 kg/m3, 6.5 Appearance silvery white Atomic properties Atomic weight 192.217 amu Atomic radius (calc.) 135 (180) pm Covalent radius 137 pm van der... iridium A crucible is a cup-shaped piece of laboratory equipment used to contain chemical compounds when heating them to very high temperatures. The receptacle is usually made of porcelain or an inert metal. One of the earliest uses of platinum was to make crucibles. More recently, metals such as nickel... crucible surrounded by an Inert is the state of doing little or nothing. In chemistry, the term inert is used to describe something that is not chemically active. The noble gases were described as being inert because they did not react with the other elements or themselves. Now scientists know that the reason that... inert Atmosphere may refer to: a celestial body atmosphere, e.g.: Earths atmosphere stellar atmospheres a unit of pressure: see atmosphere (unit) a gas mixture or artificial atmosphere ambience or mood the rap group, Atmosphere This is a disambiguation page — a navigational aid which lists other pages that might... atmosphere is used, wherein General Name, Symbol, Number Yttrium, Y, 39 Chemical series transition metals Group, Period, Block 3 (IIIB), 5, d Density, Hardness 4472 kg/m3, __ Appearance Silvery white Atomic Properties Atomic weight 88.90585 amu Atomic radius (calc.) 180 (212) pm Covalent radius 162 pm van der Waals radius no data... yttrium oxide and General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13 (IIIA), 3, p Density, Hardness 2700 kg/m3, 2.75 Appearance silvery Atomic properties Atomic weight 26.981538 amu Atomic radius (calc.) 125 pm (118 pm) Covalent radius 118 pm van der Waals radius no... aluminium oxide are melted and mixed together at a carefully controlled temperature of ca. 1980°C. A small seed crystal is attached to a rod which is lowered over the crucible until the crystal contacts the surface of the melted mixture. The seed crystal acts as a site of nucleation; the temperature is kept steady at a point where the surface of the mixture is just below the melting point. The rod is slowly and continuously rotated and retracted, and the pulled mixture crystallizes as it exits the crucible, forming a single crystal in the form of a cylindrical boule. The crystal's purity is extremely high, and it typically measures 5 cm (2 inches) in diameter and 20 cm (8 inches) long, and weighs 9,000 carats (1.75 kg or 4 pounds).


YAG's hardness (8.25) and lack of brittleness were great improvements over strontium titanate, and although its RI (1.83) and dispersion (0.028) were fairly low, they were enough to give brilliant-cut YAGs perceptible fire and good brilliance (although still much lower than diamond). A number of different colors were also produced with the addition of dopants, including yellow, red, and a vivid green which was used to imitate For other things of this name, see Emerald (disambiguation). Emerald in the rough Three cut Emeralds Emerald is a variety of the mineral beryl, colored green by trace amounts of chromium and sometimes iron. It is highly prized as a gemstone and ounce for ounce is the most valuable gemstone... emerald. Major producers included Litton Systems, Allied Chemical, Raytheon Company (NYSE: RTN) is a major United States military contractor based in Waltham, Massachusetts. At least 80 percent of Raytheons revenues are obtained from contracts with the United States government. It is the second largest military contractor in the world. William H. Swanson is the Chairman and CEO... Raytheon, and Union Carbide is a chemical manufacturer, now a subsidiary of The Dow Chemical Company. The company is most well-known for the Bhopal Disaster in 1984, in which the leakage of the highly toxic gas methyl isocyanate (MIC) killed thousands in Bhopal, India. The chairman Warren Anderson was charged with... Union Carbide; annual global production peaked at 40 million carats (8,000 kg or 17,600 pounds) in 1972 was a leap year that started on a Saturday. Events January January 2 - the Pierre Hotel Heist - Six men rob the safety deposit boxes of the Pierre Hotel in New York City. Loot is at least $4 million January 5 - President of the United States Richard Nixon orders the... 1972, but fell sharply thereafter. Commercial names for YAG included Diamonair, Diamonique, Gemonair, Replique, and Triamond.


While market saturation was one reason for the fall in YAG production levels, another was the recent introduction of the other artifical garnet important as a diamond simulant, gadolinium gallium garnet ( Germanische Glaubens-Gemeinschaft (Germanic Faith-Community) is the oldest Asatru organisation still operational. It was founded in 1907 by professor Ludwig Fahrenkrog (1867-1952) in Germany. In the 1930s they were heavily supressed by the nazis. In 1933, Rudolf von Sebettendorff was arrested and exiled. The nazis banned works of... GGG; Gd3Ga5O12). Pruduced in much the same manner as YAG (but with a lower melting point of 1750°C), GGG had an RI (1.97) close to, and a dispersion (0.045) nearly identical to diamond. GGG was also hard enough (hardness 7) and tough enough to be an effective gemstone, but its ingredients were also much more expensive than YAG's. Equally hindering was GGG's tendency to turn a dark brown upon exposure to Sunlight is also the trade name of the worlds first packaged, branded laundry soap producted by Lever Brothers. Prism splitting light Sunlight in the broad sense is the total spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered by the atmosphere, and the solar... sunlight or other Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. It can be subdivided into near UV (380–200 nm wavelength... ultraviolet source: this was due to the fact that most GGG gems were fashioned from impure material that was rejected for technological use. The SG of GGG (7.02) is also the highest of all diamond simulants and amongst the highest of all gemstones, which makes loose GGG gems easy to spot by comparing their dimensions with their expected and actual carat weights. Relative to its predecessors, GGG was never produced in significant quantities; it became more or less unheard of by the close of the 1970s. Commercial names for GGG included Diamonique II and Galliant.


1976 to present

A round brilliant-cut cubic zirconia Cubic Zirconia (or CZ) is zirconium oxide (ZrO2), a mineral that is extremely rare in nature but is widely synthesized for use as a diamond simulant. The synthesized material is hard, optically flawless and usually colourless, but may be made in a variety of... Cubic zirconia or CZ (ZrO2; General Name, Symbol, Number Zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Density, Hardness 6511 kg/m3, 5 Appearance Silvery white Atomic properties Atomic weight 91.224 amu Atomic radius (calc.) 155 (206) pm Covalent radius 148 pm van der Waals radius no data Electron... zirconium oxide—not to be confused with For the spy satellite of this codename see Zircon (satellite). Zircon dust Zircon (from Persian: sarkun, golden) is a mineral belonging to the group of nesosilicates. Its chemical formula is ZrSiO4. The crystal structure of zircon is tetragonal (crystal class: 4/m 2/m 2/m). The natural color of... zircon, a zirconium silicate) quickly dominated the diamond simulant market following its introduction in 1976 is a leap year starting on Thursday (link will take you to calendar). Events January-February January 12 - UN Security Council votes 11-1 to admit the Palestinian Liberation Organization January 15 - Would-be Gerald Ford presidential assassin Sara Jane Moore is sentenced to life in prison January 16... 1976, and it remains the most gemologically and economically important simulant. CZ had been synthesized since 1930 is a common year starting on Wednesday. Events January-February January 6 - The first diesel-engine automobile trip is completed (Indianapolis, Indiana, to New York City). January 27 - Miguel Primo de Rivera resigns January 30 - General Damaso Berenquer becomes the new prime minister of Spain February 18 - While studying... 1930 but only in The word ceramic is derived from Greek, and in its strictest sense refers to clay in all its forms. However, modern usage of the term broadens the meaning to include all inorganic non_metallic materials. Up until the 1950s or so, the most important of these were the traditional clays, made... ceramic form: the growth of single-crystal CZ would require an approach radically different than those used for previous simulants due to zirconium's extremely high melting point (2750°C), unsustainable by any crucible. The solution found involved a network of water-filled copper pipes and Radio frequency induction or RF induction is an electrical phenomenon in which an electromagnetic wave passing through a conductor causes electric current to flow through it. It is a special case of electromagnetic induction. A common use of RF induction is induction heating (also called eddy-current heating), a method... radio frequency induction coils; the latter to heat the zirconium feed powder, and the former to cool the exterior and maintain a retaining "skin" under 1 millimeter thick. CZ was thusly grown in a crucible of itself, a technique called cold crucible (in reference to the cooling pipes) or The Skull Crucible process was developed at the Lebedev Physical Institute in Moscow to manufacture cubic zirconia. Zirconium oxide powder is heated then gradually allowed to cool. Heating is accomplished by radio frequency induction using a coil wrapped around the apparatus. In order to keep the RF coil from melting... skull crucible (in reference to either the shape of the crucible or of the crystals grown).


At Temperature and air pressure can vary from one place to another on the Earth, and can also vary in the same place with time. These values, however, are very important in many chemical and physical processes, in particular with regard to measurements. Therefore, it is necessary to define standard conditions... standard pressure zirconium oxide would normally crystallize in the In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal length, as in the orthorhombic system. Two of the vectors are perpendicular, while the third makes... monoclinic rather than cubic crystal system: for cubic crystals to grow, a stabilizer must be used. This is usually General Name, Symbol, Number Yttrium, Y, 39 Chemical series transition metals Group, Period, Block 3 (IIIB), 5, d Density, Hardness 4472 kg/m3, __ Appearance Silvery white Atomic Properties Atomic weight 88.90585 amu Atomic radius (calc.) 180 (212) pm Covalent radius 162 pm van der Waals radius no data... yttrium or See also Calcium, New York, United States. General Name, Symbol, Number calcium, Ca, 20 Series alkaline earth metal Group, Period, Block 2 (IIA), 4, s Density, Hardness 1550 kg/m3, 1.75 Appearance silvery white Atomic properties Atomic weight 40.078 amu Atomic radius (calc.) 180 (194) pm Covalent radius... calcium. The skull crucible technique was first developed in Centuries: 19th century - 20th century - 21st century Decades: 1900s 1910s 1920s 1930s 1940s 1950s - 1960s - 1970s 1980s 1990s 2000s 2010s Years: 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 Events and trends The 1960s was a turbulent decade of change around the world. Many of the trends of... 1960s The French Republic or France ( French: République française or France) is a country whose metropolitan territory is located in western Europe, and which is further made up of a collection of overseas islands and territories located in other continents. France is a democracy organised as a... France, but it was perfected in the early 1970s by Soviet redirects here. For other uses, see Soviet (disambiguation). The Union of Soviet Socialist Republics (USSR) (Russian: Сою́з Сове́тских Социалисти́ческих Р... Soviet scientists under V. V. Osiko at the The Lebedev Physical Institute of the Russian Academy of Sciences is a Russian research institute specializing in physics. It can also be referred to as the Lebedev Institute of Physics or just the Lebedev Institute. It is named after Petr Nikolaevich Lebedev. In Russian it is often referred to by... Lebedev Physical Institute in Saint Basils Cathedral Moscow  listen? ( Russian/Cyrillic: Москва́, pronunciation: Moskva), capital of Russia, located on the river Moskva, and encompassing 1097.12 km2. Its coordinates are 55°45′ N 37°37′ E. The citys population... Moscow. By 1980 is a leap year starting on Tuesday. Events January-February January 1- April 1 - National steel strike in the United Kingdom January 1 - Changes to the Swedish Act of Succession creates Victoria of Sweden, Crown Princess over her younger brother January 4 - American president Jimmy Carter proclaims, with support... 1980 annual global production had reached 50 million carats (10,000 kg).


The hardness (8–8.5), RI (2.15–2.18, isotropic), dispersion (0.058–0.066), and low material cost make CZ the best and most popular simulant of diamond. Its optical and physical constants are however variable, owing to the different stabilizers used by different producers. While the visual likeness of CZ is close enough to diamond to fool most who do not handle diamond regularly, CZ will usually give certain clues. For example: it is somewhat brittle and is soft enough to possess scratches after normal use in jewelry; it is usually internally flawless and completely colorless (whereas most diamonds have some internal imperfections and a yellow tint); its SG (5.6–6) is high; and its reaction under Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. It can be subdivided into near UV (380–200 nm wavelength... ultraviolet light is a distinctive beige. Most jewelers will use a thermal probe to test all suspected CZs, a test which relies on diamond's superlative In physics, thermal conductivity, λ, is the quantity of heat transmitted, due to unit temperature gradient, in unit time under steady conditions in a direction normal to a surface of unit area, when the heat transfer is dependent only on the temperature gradient thermal conductivity = heat flow rate / (distance × temperature... thermal conductivity (CZ, like almost all other diamond simulants, are thermal Insulators are materials which prevent the flow of heat (thermal insulators) or electric charge (electrical insulators). The opposite of electrical insulators are conductors and semiconductors, which permit the flow of charge (Note: a semiconductor is strictly speaking also an insulator, since it prevents the flow of electric charge at low... insulators). CZ is made in a number of different colors meant to imitate fancy diamonds (e.g., yellow to golden brown, orange, red to pink, green, and opaque black), but most of these do not approximate the real thing. Some CZs have been given a coating of diamond-like carbon in an effort to improve their durability, but this does not fool a thermal probe.


CZ had virtually no competition until the 1998 is a common year starting on Thursday of the Gregorian calendar, and was designated the International Year of the Ocean. Events January January 1998 - A massive ice storm, caused by El Niño, strikes New England, southern Ontario and Quebec, resulting in widespread power failures, severe damage to... 1998 introduction of synthetic Moissanite was first found in 1893 as a small component of a meteorite in Arizona by Dr. Ferdinand Henri Moissan, after whom the material was named. Naturally occurring moissanite is exceedingly rare, having an appearance similar to that of diamond and a tetrahedral crystalline structure. In 1998 C3, Inc. (Charles... moissanite (SiC; Silicon carbide (SiC) or moissanite is a ceramic compound of silicon and carbon. Synthetic silicon carbide crystal aggregate: iridescent twinned crystals in foreground with untwinned tabular crystals in background. They have a metallic lustre and are razor-sharp. Most silicon carbide is man-made for use as an abrasive (when... silicon carbide). Synthetic moissanite is superior to cubic zirconia in two ways: its great hardness (9.25) and low SG (3.2). The former property results in facets that are as sometimes as crisp as a diamond's, while the latter property makes moissanite somewhat harder to spot when unset (although still disparate enough to detect). Synthetic moissanite is also more resistant to heat than any other gemstone: so much so that it can be safely set directly into molten General Name, Symbol, Number Gold, Au, 79 Chemical series transition metals Group, Period, Block 11 (IB), 6, d Density, Hardness 19300 kg/m3, 2.5 Appearance Metallic yellow Atomic properties Atomic weight 196.96655 amu Atomic radius (calc.) 135 (174) pm Covalent radius 144 pm van der Waals radius 166... gold. However, its dispersion (0.104) is over twice that of diamond; it is also anisotropic with an RI of 2.648–2.691 and a high birefringence of 0.043. This manifests as the same "drunken vision" effect seen in synthetic rutile, although to a lesser degree. All synthetic moissanite is cut with the table perpendicular to the optic axis in order to hide this property from above, but when viewed under magnification at only a slight tilt the doubling of facets (and any inclusions) is readily apparent.


The inclusions seen in synthetic moissanite are also characteristic: most will have fine, white, subparallel growth tubes or needles oriented perpedicular to the stone's table. It is conceivable that these growth tubes could be mistaken for laser drill holes that are sometimes seen in diamond (see This article addresses treatments designed to enhance the gemological characteristics of diamond. For a broader discussion of diamonds, see diamond. For other uses of the word diamond, see diamond (disambiguation). Diamond enhancements are specific treatments, performed on natural and sometimes synthetic diamonds (usually those already cut and polished into gems... diamond enhancement), but the tubes will be noticeably doubled in moissanite due to its birefringence. Like synthetic rutile, current moissanite production is also plagued by an as of yet inescapable tint, which is usually a brownish green. A limited range of fancy colors have been produced as well, the two most common being blue and green. Gem-quality synthetic moissanite is produced by only one company, Charles & Colvard. Its limited availability makes moissanite about 120 times more expensive than cubic zirconia.


When synthetic moissanite was first introduced it made quite a stir: stories of widespread In the broadest sense a fraud is any crime (or civil wrong) for gain that utilises some deception practiced on the victim as its principal method. In law, fraud is the crime or offense of deliberately deceiving another in order to damage them -- usually, to obtain property or services from... fraud were circulated by the press, with claims that synthetic moissanite was indistinguishable from diamond even by experts. The aforementioned properties clearly demonstrate this to be false: the only people fooled by synthetic moissanite were those who relied too heavily on thermal probes. This is because, like diamond, moissanite has a high thermal conductivity; probes manufactured before synthetic moissanite's introduction therefore registered synthetic moissanite as diamond. More sophisticated thermal probes are now able to differentiate moissanite from diamond, and Charles & Colvard also manufacture their own proprietary device which relies on moissanite's greater opacity to ultraviolet light.


Natural simulants

Natural Minerals are natural compounds formed through geological processes. The term mineral encompasses not only the materials chemical composition but also the mineral structures. Minerals range in composition from pure elements and simple salts to very complex silicates with thousands of known forms (organic compounds are usually excluded). The study... minerals that (when cut) optically resemble white diamonds are rare, because the trace impurities usually present in natural minerals tend to impart color. The earliest simulants of diamond were colorless For other uses of this word, see Quartz (disambiguation). Quartz is the second most abundant mineral in the Earths crust. It has a hexagonal crystal structure made of trigonal crystallized silica (silicon dioxide, SiO2), with a hardness of 7 on the Mohs scale. Density is 2.6g/cm³. The... quartz, This article is about the mineral or gemstone, for other uses see: Topaz (disambiguation). Topaz The mineral topaz is a silicate of aluminium and fluorine with the chemical formula (AlF)2SiO4. It is orthorhombic and its crystals are mostly prismatic terminated by pyramidal and other faces, the basal pinacoid often... topaz, and This article is about the mineral, for the rifle see Beryl assault rifle. Beryl The mineral beryl is a beryllium aluminium cyclosilicate with the chemical formula Be3Al2(SiO3)6. The hexagonal crystals of beryl may be very small or range to several meters in size. Terminated crystals are relatively rare... beryl (goshenite); they are all common minerals with above-average hardness (7–8), but all have low RIs and correspondingly low dispersions. Well-formed quartz crystals are sometimes offered as "diamonds," a popular example being the so-called "Herkimer diamonds" mined in Herkimer County is a county located in the state of New York. As of 2000, the population is 64,427. It is named after General Nicholas Herkimer, who died from battle wounds in 1777 after taking part in the Battle of Oriskany. Its county seat is Herkimer. History When counties... Herkimer County, New York. Topaz's SG (3.50–3.57) also falls within the range of diamond.


From a historical perspective, the most notable natural simulant of diamond is For the spy satellite of this codename see Zircon (satellite). Zircon dust Zircon (from Persian: sarkun, golden) is a mineral belonging to the group of nesosilicates. Its chemical formula is ZrSiO4. The crystal structure of zircon is tetragonal (crystal class: 4/m 2/m 2/m). The natural color of... zircon. It is also fairly hard (7.5), but more importantly shows perceptible fire when cut, due to its high dispersion of 0.039. Colorless zircon has been mined in The Democratic Socialist Republic of Sri Lanka (ශ්රී ලංකා in Sinhala / இலங்கை in Tamil) (known as Ceylon before 1972) is a tropical island nation off the southeast coast of the Indian subcontinent. The island was known in ancient times... Sri Lanka for over 2,000 years; prior to the advent of modern Mineralogy is an earth science that involves the chemistry, crystal structure, and physical (including optical) properties of minerals. Studies also include the processes of mineral creation and destruction. The International Mineralogical Association is an organization whose members are organizations representing mineralogists in individual countries. Its activities include managing naming of... mineralogy, colorless zircon was thought to be an inferior form of diamond. It was called "Matara diamond" after its source location. It is still encountered as a diamond simulant, but differentiation is easy due to zircon's anisotropy and strong birefringence (0.059). It is also notoriously brittle and often shows wear on the girdle and facet edges.


Much less common than colorless zircon is colorless Scheelite is a calcium tungstate mineral with the chemical formula CaWO4. It is an important ore of tungsten. Well-formed crystals are sought by collectors and are occasionally fastened into gemstones when suitably free of flaws. Scheelite has been synthesized via the Czochralski process; the material produced may be used... scheelite. Its dispersion (0.026) is also high enough to mimic diamond, but although it is highly lustrous its hardness is much too low (4.5–5.5) to maintain a good polish. It is also anisotropic and fairly dense (SG 5.9–6.1). Synthetic scheelite produced via the Czochralski process is available, but it has never been widely used as a diamond simulant. Due to the scarcity of natural gem-quality scheelite, synthetic scheelite is much more likely to simulate it than diamond. A similar case is the orthorhombic Carbonate is an anion with a charge of -2 and an empirical formula of CO32-. An aqueous solution of carbon dioxide contains a minute amount of H2CO3, called carbonic acid, which dissociates to form hydrogen ions and carbonate ions. It would be a fairly strong acid if carbonic acid existed... carbonate Sample of cerussite-bearing quartzite Cerussite (also known as Horn silver, Lead carbonate, White lead ore) is a mineral consisting of lead carbonate (PbCO3), and an important ore of lead. The name (sometimes erroneously spelt cerusite) is from the Latin cerussa, white lead. Cerussa nativa was mentioned by K. Gesner... cerussite, which is so fragile (very brittle with four directions of good cleavage) and soft (hardness 3.5) that it is never seen set in jewelry, and only occasionally seen in gem collections because it is so difficult to cut. Cerussite gems have an adamantine luster, high RI (1.804–2.078), and high dispersion (0.051), making them attractive and valued collector's pieces. Aside from softness, they are easily distinguished by cerussite's high density (SG 6.51) and anisotropy with extreme birefringence (0.271).


Due to their rarity fancy-colored diamonds are also imitated, and zircon can serve this purpose too. Applying heat treatment to brown zircon can create several bright colors: these are most commonly sky-blue, golden yellow, and red. Blue zircon is very popular, but it is not necessarily color stable; prolonged exposure to ultraviolet light (including the UV component in sunlight) tends to bleach the stone. Heat treatment also imparts greater brittleness to zircon and characteristic inclusions.


Another fragile candidate mineral is Sphalerite sample Another sphalerite sample Sphalerite (ZnS) is a mineral that is the chief ore of zinc. It consists largely of zinc sulfide in crystalline form but often contains some iron as (Zn,Fe)S. It is usually found in association with galena, pyrite, and other sulfides along with calcite... sphalerite (zinc blende). Gem-quality material is usually a strong yellow to honey brown, orange, red, or green; its very high RI (2.37) and dispersion (0.156) make for an extremely lustrous and fiery gem, and it is also isotropic. But here again, its low hardness (2.5–4) and perfect dodecahedral cleavage preclude sphalerite's wide use in jewelry. Two calcium-rich members of the The Garnet group of minerals show crystals with a habit of dodecahedrons and trapezohedrons. They are nesosilicates with the same general formula, A3B2(SiO4)3. Many different chemical elements are included in the several varieties of garnet, including calcium, magnesium, aluminium, iron2+, iron3+, chromium, manganese, and titanium. Garnets show no... garnet group fare much better: these are grossular (usually brownish orange, rarely colorless, yellow, green, or pink) and andradite. The latter is the rarest and most costly of the garnets, with three of its varieties—topazolite (yellow), melanite (black), and demantoid (green)—sometimes seen in jewelry. Demantoid (literally "diamond-like") especially has been prized as a gemstone since its discovery in the The Ural Mountains, (Russian: Ура́льские го́ры = Ура́л) also known simply as the Urals, are a mountain range that run roughly north and south through western Russia. The Urals extend 2500 km from the... Ural Mountains in 1868 was a leap year starting on Wednesday (see link for calendar). Events January 3 - Meiji Emperor declares Meiji Restoration, his own restoration to full power, against the supporters of the Tokugawa Shogunate. January 10 - Shogun Tokugawa Yoshinobu declares emperors declaration illegal and attacks Kyoto. Pro-Emperor forces drive... 1868; it is a noted feature of antique The Russian Federation ( Russian: Росси́йская Федера́ция, transliteration: Rossiyskaya Federatsiya or Rossijskaja Federacija), or Russia (Russian: Росси́я, transliteration: Rossiya or Rossija), is a country that stretches... Russian and Alfons Mucha, lithographed poster, 1898 Art Nouveau (French for New art) is an art and design style that peaked in popularity at the turn of the 20th century. Other, more localized terms for the cluster of self-consciously radical, somewhat mannered reformist chic that formed a prelude to 20th-century... Art Nouveau jewelry. Titanite or sphene is a calcium titanium nesosilicate mineral, CaTiSiO5. Trace impurities of iron and aluminium are invariably present. Also commonly present are rare earth metals including cerium and yttrium. Titanite, which is named for its titanium content, occurs as translucent to transparent, reddish brown, gray, yellow, green, or red... Titanite or sphene is also seen in antique jewelry; it is typically some shade of chartreuse and has a luster, RI (1.885–2.050), and dispersion (0.051) high enough to be mistaken for diamond, yet it is anisotropic (a high birefringence of 0.105–0.135) and soft (hardness 5.5).


Discovered the Centuries: 19th century - 20th century - 21st century Decades: 1900s 1910s 1920s 1930s 1940s 1950s - 1960s - 1970s 1980s 1990s 2000s 2010s Years: 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 Events and trends The 1960s was a turbulent decade of change around the world. Many of the trends of... 1960s, the rich green Tsavorite can be considered a new gemstone since it was unknown before its discovery in Kenya in the 1960s. It is a member of the garnet family group grossularite (a calcium-aluminum garnet Ca3Al2Si3O12) in which trace amounts of vanadium or chromium provide the green color. The name tsavorite comes... tsavorite variety of grossular is also very popular. Both grossular and andradite are isotropic and have relatively high RIs (ca. 1.74 and 1.89, respectively) and high dispersions (0.027 and 0.057), with demantoid's exceeding diamond. However, both have a low hardness (6.5–7.5) and invariably possess inclusions atypical of diamond—the byssolite "horsetails" seen in demantoid are one striking example. Furthermore, most are very small, typically under one half carat in weight. Their lusters range from vitreous to subadamantine, to almost metallic in the usually opaque melanite, which has been used to simulate black diamond. Some natural spinel is also a deep black and could serve this same purpose.


Composites

Because strontium titanate and glass are too soft to survive use as a ring stone, they have been used in the construction of composite or doublet diamond simulants. The two materials are used for the bottom portion (pavilion) of the stone, and in the case of strontium titanate, a much harder material—usually colorless synthetic spinel or sapphire—is used for the top half (crown). In glass doublets, the top portion is made of Almandine, or almandite, is a name applied to certain kinds of precious garnet, being apparently a corruption of alabandicus, which is the name applied by Pliny to a stone found or worked at Alabanda, a town in Caria in Asia Minor. Almandine is an iron alumina garnet, of deep red... almandine garnet; it is usually a very thin slice which does not modify the stone's overall body color. There have even been reports of diamond-on-diamond doublets, where a creative entrepreneur has used two small pieces of rough to create one larger stone.


In strontium titanate and diamond-based doublets, an Epoxy or polyepoxide is a thermosetting epoxide polymer that cures when mixed with a catalyzing agent or hardener. Most common epoxy resins are produced from a reaction between Epichorohydrin & Bisphenol A. The first commercial attempts to prepare resins from epichlorohydrin occurred in 1927 in the United States. Credit for... epoxy is used to adhere the two halves together. The epoxy may fluoresce under UV light, and there may be residue on the stone's exterior. The garnet top of a glass doublet is physically fused to its base, but in it and the other doublet types there are usually flattened air bubbles seen at the junction of the two halves. A join line is also readily visible whose position is variable; it may be above or below the girdle, sometimes at an angle, but rarely along the girdle itself.


See also

  • This article addresses treatments designed to enhance the gemological characteristics of diamond. For a broader discussion of diamonds, see diamond. For other uses of the word diamond, see diamond (disambiguation). Diamond enhancements are specific treatments, performed on natural and sometimes synthetic diamonds (usually those already cut and polished into gems... Diamond enhancement
  • Jewelers set diamonds in groups of similar colors. A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. However, in reality almost no gem-sized natural diamonds are absolutely perfect. The color of a diamond may be affected by chemical impurities and/or structural defects... Diamond color
  • This article addresses the many styles of diamond cut. For a broader discussion of diamonds, see diamond. For other uses of the word diamond, see diamond (disambiguation). In order to best utilize a diamond gemstones superlative material properties, a number of different diamond cuts have been developed. A diamond... Diamond cut
  • Diamond clarity is a quality of diamonds relating to the existence and visual appearance of internal defects of a diamond called inclusions, and surface defects called blemishes. Clarity is one of the four Cs of diamond grading, the others being carat, color, and cut. Inclusions may be crystals of a... Diamond clarity
  • This article addresses the material properties of diamond. For a broader discussion of diamonds, see diamond. For other uses of the word diamond, see diamond (disambiguation). Diamond is transparent to opaque, optically isotropic crystalline carbon. It is the hardest naturally-occurring material known—owing to its strong covalent bonding... Material properties of diamond
  • Synthetic diamond is diamond produced through chemical or physical processes in a laboratory. Like naturally occurring diamond it is composed of a three-dimensional carbon crystal. Synthetic diamonds are also called cultured diamonds, manufactured diamonds, and artificial diamonds. History Synthetic diamonds were first produced on February 16, 1953 in Stockholm... Synthetic diamond

References

  • Hall, Cally. (1994). Gemstones, p. 63, 70, 121. Eyewitness Handbooks; Kyodo Printing Co., Singapore. ISBN 0773727620
  • Nassau, Kurt. (1980). Gems made by man, pp. 203–241. Gemological Institute of America; Santa Monica, California. ISBN 087330161
  • O'Donoghue, Michael, and Joyner, Louise. (2003). Identification of gemstones, pp. 12–19. Butterworth-Heinemann, Great Britain. ISBN 0750655127
  • Pagel-Theisen, Verena. (2001). Diamond grading ABC: The manual (9th ed.), pp. 298–313. Rubin & Son n.v.; Antwerp, Belgium. ISBN 3980043460
  • Schadt, H. (1996). Goldsmith's art: 5000 years of jewelry and hollowware, p. 141. Arnoldsche Art Publisher; Stuttgard, New York. ISBN 3925369546
  • Webster, Robert, and Read, Peter G. (Ed.) (2000). Gems: Their sources, descriptions and identification (5th ed.), pp. 65–71. Butterworth-Heinemann, Great Britain. ISBN 0750616741

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Diamond - Wikipedia, the free encyclopedia (8443 words)
Diamond is the hardest known naturally occurring material, scoring 10 on the relative Mohs scale of mineral hardness and having an absolute hardness value of between 167 and 231 gigapascals in various tests.
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Diamonds which are not cut to the specifications of Tolkowsky's round brilliant shape (or subsequent variations) are known as "fancy cuts." Popular fancy cuts include the baguette (from the French, resembling a loaf of bread), marquise, princess (square outline), heart, briolette (a form of the rose cut), and pear cuts.
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Diamond is a transparent, optically isotropic crystal with a refractive index of 2.417, a high dispersion of 0.044, and a specific gravity of 3.52.
In the late 18th century, diamonds were demonstrated to be made of carbon by the rather expensive experiment of igniting a diamond (by means of a burning-glass) in an oxygen atmosphere and showing that carbonic acid gas (carbon dioxide) was the product of the combustion.
In response to public concerns that their diamond purchases were contributing to war and human rights abuses in central Africa, the diamond industry and diamond-trading nations introduced the Kimberley Process aimed at ensuring that conflict diamonds do not becoming intermixed with the diamonds not controlled by such rebel groups.
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