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FAMOUS DIAMONDS

The name diamond is derived from the ancient Greek αδάμας (adámas), "proper", "unalterable", "unbreakable, untamed", from ἀ- (a-), "un-" +δαμάω (damáō), "I overpower, I tame". Diamonds are thought to have been first recognized and mined in India, where significant alluvial deposits of the stone could be found many centuries ago along the rivers Penner, Krishna and Godavari. Diamonds have been known in India for at least 3,000 years but most likely 6,000 years. Diamonds have been treasured as gemstones since their use as religious icons in ancient India. Their usage in engraving tools also dates to early human history. The popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns. In 1772, Antoine Lavoisier used a lens to concentrate the rays of the sun on a diamond in an atmosphere of oxygen, and showed that the only product of the combustion was carbon dioxide, proving that diamond is composed of carbon. Later in 1797, Smithson Tennant repeated and expanded that experiment. By demonstrating that burning diamond and graphite (charcoal) releases the same amount of gas he established the chemical equivalence of these substances.[8] The most familiar use of diamonds today is as gemstones used for adornment, a use which dates back into antiquity. The dispersion of white light into spectral colors is the primary gemological characteristic of gem diamonds. In the 20th century, experts in gemology have developed methods of grading diamonds and other gemstones based on the characteristics most important to their value as a gem. Four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds: these are carat, cut, color, and clarity. A large, flawless diamond is known as a paragon.  Theoretically predicted phase diagram of carbon Diamond and graphite are two allotropesof carbon: pure forms of the same element that differ in structure. A diamond is a transparent crystal of tetrahedrallybonded carbon atoms (sp3) that crystallizes into thediamond lattice which is a variation of the face centered cubic structure. Diamonds have been adapted for many uses because of the material's exceptional physical characteristics. Most notable are its extreme hardness and thermal conductivity (900–2,320 W·m−1·K−1), as well as wide bandgap and high optical dispersion.[11]Above 1,700 °C (1,973 K / 3,583 °F) in vacuum or oxygen-free atmosphere, diamond converts to graphite; in air, transformation starts at ~700 °C. Naturally occurring diamonds have a density ranging from 3.15–3.53 g/cm3, with pure diamond close to3.52 g/cm3. Despite the hardness of diamonds, the chemical bonds that hold the carbon atoms in diamonds together are weaker than those that hold together the other form of pure carbon, graphite. The difference is that in diamonds, the bonds form an inflexible three-dimensional lattice. In graphite, the atoms are tightly bonded into sheets, which can slide easily over one another. Hardness Diamond is the hardest natural material known, where hardness is defined as resistance to scratching and is graded between 1 (softest) and 10 (hardest) using the Mohs scale of mineral hardness. Diamond has a hardness of 10 (hardest) on this scale. Diamond's hardness has been known since antiquity, and is the source of its name. Diamond hardness depends on its purity, crystalline perfection and orientation: hardness is higher for flawless, pure crystals oriented to the<111> direction (along the longest diagonal of the cubic diamond lattice).[15] Therefore, whereas it might be possible to scratch some diamonds with other materials, such as boron nitride, the hardest diamonds can only be scratched by other diamonds and nanocrystalline diamond aggregates. The hardness of diamond contributes to its suitability as a gemstone. Because it can only be scratched by other diamonds, it maintains its polish extremely well. Unlike many other gems, it is well-suited to daily wear because of its resistance to scratching—perhaps contributing to its popularity as the preferred gem in engagement or wedding rings, which are often worn every day. The hardest natural diamonds mostly originate from the Copeton and Bingara fields located in the New England area in New South Wales, Australia. These diamonds are generally small, perfect to semiperfect octahedra, and are used to polish other diamonds. Their hardness is associated with the crystal growth form, which is single-stage crystal growth. Most other diamonds show more evidence of multiple growth stages, which produce inclusions, flaws, and defect planes in the crystal lattice, all of which affect their hardness. It is possible to treat regular diamonds under a combination of high pressure and high temperature to produce diamonds that are harder than the diamonds used in hardness gauges. Somewhat related to hardness is another mechanical property toughness, which is a material's ability to resist breakage from forceful impact. The toughness of natural diamond has been measured as 2.0 MPa·m1/2, and the critical stress intensity factor is 3.4 MN·m−3/2. Those values are good compared to other gemstones, but poor compared to most engineering materials. As with any material, the macroscopic geometry of a diamond contributes to its resistance to breakage. Diamond has a cleavage plane and is therefore more fragile in some orientations than others. Diamond cutters use this attribute to cleave some stones, prior to faceting.[19] Electrical conductivity Other specialized applications also exist or are being developed, including use as semiconductors: some blue diamonds are natural semiconductors, in contrast to most diamonds, which are excellent electrical insulators. The conductivity and blue color originate from boron impurity. Boron substitutes for carbon atoms in the diamond lattice, donating a hole into the valence band. Substantial conductivity is commonly observed in nominally undoped diamond grown by chemical vapor deposition. This conductivity is associated with hydrogen-related species adsorbed at the surface, and it can be removed by annealing or other surface treatments. Color Main article: Diamond color Brown diamonds at the National Museum of Natural History in Washington, D.C Diamond has a wide bandgap of 5.5 eV corresponding to the deep ultravioletwavelength of 225 nanometers. This means pure diamond should transmit visible light and appear as a clear colorless crystal. Colors in diamond originate from lattice defects and impurities. The diamond crystal lattice is exceptionally strong and only atoms of nitrogen, boron and hydrogen can be introduced into diamond during the growth at significant concentrations (up to atomic percents). Transition metals Ni and Co, which are commonly used for growth of synthetic diamond by high-pressure high-temperature techniques, have been detected in diamond as individual atoms; the maximum concentration is 0.01% for Ni[23] and even much less for Co. Virtually any element can be introduced to diamond by ion implantation.[24] Nitrogen is by far the most common impurity found in gem diamonds. Nitrogen is responsible for the yellow and brown color in diamonds. Boron is responsible for the gray blue colors.[11] Color in diamond has two additional sources: irradiation (usually by alpha particles), that causes the color in green diamonds; and plastic deformation of the diamond crystal lattice. Plastic deformation is the cause of color in some brown[25] and perhaps pink and red diamonds.[26] In order of rarity, colorless diamond, by far the most common, is followed by yellow and brown, by far the most common colors, then by blue, green, black, translucent white, pink, violet, orange, purple, and the rarest, red.[19] "Black", or Carbonado, diamonds are not truly black, but rather contain numerous dark inclusions that give the gems their dark appearance. Colored diamonds contain impurities or structural defects that cause the coloration, while pure or nearly pure diamonds are transparent and colorless. Most diamond impurities replace a carbon atom in the crystal lattice, known as a carbon flaw. The most common impurity, nitrogen, causes a slight to intense yellow coloration depending upon the type and concentration of nitrogen present.[19] The Gemological Institute of America(GIA) classifies low saturation yellow and brown diamonds as diamonds in the normal color range, and applies a grading scale from "D" (colorless) to "Z" (light yellow). Diamonds of a different color, such as blue, are called fancy colored diamonds, and fall under a different grading scale.[19] In 2008, the Wittelsbach Diamond, a 35.56-carat (7.11 g) blue diamond once belonging to the King of Spain, fetched over US$24 million at a Christie's auction.[27] In May 2009, a 7.03-carat (1.41 g) blue diamond fetched the highest price per carat ever paid for a diamond when it was sold at auction for 10.5 million Swiss francs (6.97 million euro or US$9.5 million at the time).[28] That record was however beaten the same year: a Template:Convert/ct vivid pink diamond was sold for $10.8 million in Hong Kong on December 1, 2009.[29] Identification Diamonds can be identified by their high thermal conductivity. Their high refractive index is also indicative, but other materials have similar refractivity. Diamonds cut glass, but this does not positively identify a diamond because other materials, such as quartz, also lie above glass on the Mohs scale and can also cut it. Diamonds can scratch other diamonds, but this can result in damage to one or both stones. Hardness tests are infrequently used in practical gemology because of their potentially destructive nature.[14] The extreme hardness and high value of diamond means that gems are typically polished slowly using painstaking traditional techniques and greater attention to detail than is the case with most other gemstones;[8] these tend to result in extremely flat, highly polished facets with exceptionally sharp facet edges. Diamonds also possess an extremely high refractive index and fairly high dispersion. Taken together, these factors affect the overall appearance of a polished diamond and most diamantaires still rely upon skilled use of a loupe (magnifying glass) to identify diamonds 'by eye'. Natural history The formation of natural diamond requires very specific conditions—exposure of carbon-bearing materials to high pressure, ranging approximately between 45 and 60 kilobars (4.5 and 6 GPa), but at a comparatively low temperature range between approximately 900–1300 °C. These conditions are met in two places on Earth; in the lithospheric mantle below relatively stable continental plates, and at the site of a meteorite strike. Formation in cratons One face of an uncut octahedral diamond, showing trigons (of positive and negative relief) formed by natural chemical etching The conditions for diamond formation to happen in the lithospheric mantle occur at considerable depth corresponding to the requirements of temperature and pressure. These depths are estimated between 140 and 190 km though occasionally diamonds have crystallized at depths about 300 km as well. The rate at which temperature changes with increasing depth into the Earth varies greatly in different parts of the Earth. In particular, under oceanic plates the temperature rises more quickly with depth, beyond the range required for diamond formation at the depth required. The correct combination of temperature and pressure is only found in the thick, ancient, and stable parts of continental plates where regions of lithosphere known as cratons exist. Long residence in the cratonic lithosphere allows diamond crystals to grow larger.[32] The slightly misshapen octahedral shape of this rough diamond crystal in matrix is typical of the mineral. Its lustrous faces also indicate that this crystal is from a primary deposit. Through studies of carbon isotope ratios (similar to the methodology used in carbon dating, except with the stable isotopes C-12 and C-13), it has been shown that the carbon found in diamonds comes from both inorganic and organic sources. Some diamonds, known as harzburgitic, are formed from inorganic carbon originally found deep in the Earth's mantle. In contrast, eclogitic diamonds contain organic carbon from organic detritus that has been pushed down from the surface of the Earth's crust throughsubduction (see plate tectonics) before transforming into diamond. These two different source of carbon have measurably different 13C:12C ratios. Diamonds that have come to the Earth's surface are generally quite old, ranging from under 1 billion to 3.3 billion years old. This is 22% to 73% of the age of the Earth.[32] Diamonds occur most often as euhedral or rounded octahedra and twinned octahedra known as macles. As diamond's crystal structure has a cubic arrangement of the atoms, they have many facets that belong to a cube, octahedron, rhombicosidodecahedron, tetrakis hexahedron or disdyakis dodecahedron. The crystals can have rounded off and unexpressive edges and can be elongated. Sometimes they are found grown together or form double "twinned" crystals at the surfaces of the octahedron. These different shapes and habits of some diamonds result from differing external circumstances. Diamonds (especially those with rounded crystal faces) are commonly found coated innyf, an opaque gum-like skin.[33] Deposition in meteorite impact craters Not all diamonds found on Earth originated here. A type of diamond called carbonado that is found in South America and Africa may have been deposited there via an asteroid impact (not formed from the impact) about 3 billion years ago. These diamonds may have formed in the intrastellar environment, but as of 2008, there was no scientific consensus on how carbonado diamonds originated.[34][35] Diamonds can also form under other naturally occurring high-pressure conditions. Very small diamonds of micrometer and nanometer sizes, known as microdiamonds or nanodiamonds respectively, have been found in meteorite impact craters. Such impact events create shock zones of high pressure and temperature suitable for diamond formation. Impact-type microdiamonds can be used as an indicator of ancient impact craters.[31] Surfacing Schematic diagram of a volcanic pipe Diamond-bearing rock is brought close to the surface through deep-origin volcanic eruptions. The magma for such a volcano must originate at a depth where diamonds can be formed[32]—150 km (93 mi) or more (three times or more the depth of source magma for most volcanoes). This is a relatively rare occurrence. These typically small surface volcanic craters extend downward in formations known as volcanic pipes.[32] The pipes contain material that was transported toward the surface by volcanic action, but was not ejected before the volcanic activity ceased. During eruption these pipes are open to the surface, resulting in open circulation; many xenoliths of surface rock and even wood and fossils are found in volcanic pipes. Diamond-bearing volcanic pipes are closely related to the oldest, coolest regions of continental crust (cratons). This is because cratons are very thick, and their lithospheric mantle extends to great enough depth that diamonds are stable. Not all pipes contain diamonds, and even fewer contain enough diamonds to make mining economically viable. The magma in volcanic pipes is usually one of two characteristic types, which cool into igneous rock known as either kimberlite or lamproite. The magma itself does not contain diamond; instead, it acts as an elevator that carries deep-formed rocks (xenoliths), minerals (xenocrysts), and fluids upward. These rocks are characteristically rich in magnesium-bearing olivine, pyroxene, and amphibole minerals[ which are often altered to serpentine by heat and fluids during and after eruption. Certain indicator minerals typically occur within diamantiferous kimberlites and are used as mineralogical tracers by prospectors, who follow the indicator trail back to the volcanic pipe which may contain diamonds. These minerals are rich inchromium (Cr) or titanium (Ti), elements which impart bright colors to the minerals. The most common indicator minerals are chromiumgarnets (usually bright red chromium-pyrope, and occasionally green ugrandite-series garnets), eclogitic garnets, orange titanium-pyrope, red high-chromium spinels, dark chromite, bright green chromium-diopside, glassy green olivine, black picroilmenite, and magnetite. Kimberlite deposits are known as blue ground for the deeper serpentinized part of the deposits, or as yellow ground for the near surface smectite clayand carbonate weathered and oxidized portion.[32] Once diamonds have been transported to the surface by magma in a volcanic pipe, they may erode out and be distributed over a large area. A volcanic pipe containing diamonds is known as a primary source of diamonds. Secondary sources of diamonds include all areas where a significant number of diamonds have been eroded out of their kimberlite or lamproite matrix, and accumulated because of water or wind action. These include alluvial deposits and deposits along existing and ancient shorelines, where loose diamonds tend to accumulate because of their size and density. Diamonds have also rarely been found in deposits left behind by glaciers (notably in Wisconsin andIndiana); in contrast to alluvial deposits, glacial deposits are minor and are therefore not viable commercial sources of diamond.[32] Production Diamond output in 2005 See also: List of diamond mines Approximately 130,000,000 carats (26,000 kg) of diamonds are mined annually, with a total value of nearly US$9 billion, and about 100,000 kg (220,000 lb) are synthesized annually.[36] Roughly 49% of diamonds originate from central and southern Africa, although significant sources of the mineral have been discovered in Canada, India, Russia, Brazil, and Australia. They are mined from kimberlite and lamproite volcanic pipes, which can bring diamond crystals, originating from deep within the Earth where high pressures and temperatures enable them to form, to the surface. The mining and distribution of natural diamonds are subjects of frequent controversy such as concerns over the sale of blood diamonds or conflict diamonds by African paramilitary groups.The diamond supply chain is controlled by a limited number of powerful businesses, and is also highly concentrated in a small number of locations around the world . Only a very small fraction of the diamond ore consists of actual diamonds. The ore is crushed, during which care is required not to destroy larger diamonds, and then sorted by density. Today, diamonds are located in the diamond-rich density fraction with the help of X-ray fluorescence, after which the final sorting steps are done by hand. Before the use of X-rays became commonplace,[39] the separation was done with grease belts; diamonds have a stronger tendency to stick to grease than the other minerals in the ore.[19] Historically diamonds were found only in alluvial deposits in southern India.[40] India led the world in diamond production from the time of their discovery in approximately the 9th century BC[4][41] to the mid-18th century AD, but the commercial potential of these sources had been exhausted by the late 18th century and at that time India was eclipsed by Brazil where the first non-Indian diamonds were found in 1725.[4]Currently, one of the most prominent Indian mines is located at Panna.[42] Diamond extraction from primary deposits (kimberlites and lamproites) started in the 1870s after the discovery of the Diamond Fields in South Africa.[43] Production has increased over time and now an accumulated total of 4,500,000,000 carats (900,000 kg) have been mined since that date.[44] Twenty percent of that amount has been mined in the last five years, and during the last 10 years, nine new mines have started production; four more are waiting to be opened soon. Most of these mines are located in Canada, Zimbabwe, Angola, and one in Russia.[44] In the U.S., diamonds have been found in Arkansas, Colorado, and Montana.[45][46] In 2004, the discovery of a microscopic diamond in the U.S. led to the January 2008 bulk-sampling of kimberlite pipes in a remote part of Montana.[46] Today, most commercially viable diamond deposits are in Russia (mostly in Sakha Republic, for example Mir pipe and Udachnaya pipe),Botswana, Australia (Northern and Western Australia) and the Democratic Republic of Congo.[47] In 2005, Russia produced almost one-fifth of the global diamond output, reports the British Geological Survey. Australia boasts the richest diamantiferous pipe, with production from theArgyle diamond mine reaching peak levels of 42 metric tons per year in the 1990s.[45][48] There are also commercial deposits being actively mined in the Northwest Territories of Canada and Brazil.[37] Diamond prospectors continue to search the globe for diamond-bearing kimberlite and lamproite pipes. Controversial sources Main articles: Kimberley Process, Blood diamond, and Child labour in the diamond industry In some of the more politically unstable central African and west African countries, revolutionary groups have taken control of diamond mines, using proceeds from diamond sales to finance their operations. Diamonds sold through this process are known as conflict diamonds or blood diamonds.[38] Major diamond trading corporations continue to fund and fuel these conflicts by doing business with armed groups. In response to public concerns that their diamond purchases were contributing to war and human rights abuses in central and western Africa, the United Nations, the diamond industry and diamond-trading nations introduced the Kimberley Process in 2002.[49] The Kimberley Process aims to ensure that conflict diamonds do not become intermixed with the diamonds not controlled by such rebel groups. This is done by requiring diamond-producing countries to provide proof that the money they make from selling the diamonds is not used to fund criminal or revolutionary activities. Although the Kimberley Process has been moderately successful in limiting the number of conflict diamonds entering the market, some still find their way in. Conflict diamonds constitute 2–3% of all diamonds traded.[50] Two major flaws still hinder the effectiveness of the Kimberley Process: (1) the relative ease of smuggling diamonds across African borders, and (2) the violent nature of diamond mining in nations that are not in a technical state of war and whose diamonds are therefore considered "clean".[49] The Canadian Government has set up a body known as Canadian Diamond Code of Conduct[51] to help authenticate Canadian diamonds. This is a stringent tracking system of diamonds and helps protect the "conflict free" label of Canadian diamonds.[52] Commercial markets See also: Diamonds as an investment A round brilliant cut diamond set in a ring The diamond industry can be separated into two distinct categories: one dealing with gem-grade diamonds and another for industrial-grade diamonds. While a large trade in both types of diamonds exists, the two markets act in dramatically different ways. Gemstones and their distribution Main article: Diamond (gemstone) A large trade in gem-grade diamonds exists. Unlike other commodities, such as most precious metals, there is a substantial mark-up in the retail sale of gem diamonds.[53] There is a well-established market for resale of polished diamonds (e.g. pawnbroking, auctions, second-hand jewelry stores, diamantaires, bourses, etc.). One hallmark of the trade in gem-quality diamonds is its remarkable concentration: wholesale trade and diamond cutting is limited to just a few locations; In 2003, 92% of the world's diamonds were cut and polished in Surat, India.[54] Other important centers of diamond cutting and trading are Antwerp, where the International Gemological Institute is based, London, New York City, Tel Aviv, and Amsterdam. A single company—De Beers—controls a significant proportion of the trade in diamonds.[55] They are based in Johannesburg, South Africa and London, England. One contributory factor is the geological nature of diamond deposits: several large primary kimberlite-pipe mines each account for significant portions of market share (such as the Jwaneng mine in Botswana, which is a single large pit operated by De Beers that can produce between 12,500,000 carats (2,500 kg) to 15,000,000 carats (3,000 kg) of diamonds per year,[56]) whereas secondary alluvial diamond deposits tend to be fragmented amongst many different operators because they can be dispersed over many hundreds of square kilometers (e.g., alluvial deposits in Brazil). The production and distribution of diamonds is largely consolidated in the hands of a few key players, and concentrated in traditional diamond trading centers, the most important being Antwerp, where 80% of all rough diamonds, 50% of all cut diamonds and more than 50% of all rough, cut and industrial diamonds combined are handled.[57] This makes Antwerp a de facto "world diamond capital". Another important diamond center is New York City, where almost 80% of the world's diamonds are sold, including auction sales.[57] The DeBeers company, as the world's largest diamond miner holds a dominant position in the industry, and has done so since soon after its founding in 1888 by the British imperialist Cecil Rhodes. De Beers owns or controls a significant portion of the world's rough diamond production facilities (mines) anddistribution channels for gem-quality diamonds. The Diamond Trading Company (DTC) is a subsidiary of De Beers and markets rough diamonds from De Beers-operated mines. De Beers and its subsidiaries own mines that produce some 40% of annual world diamond production. For most of the 20th century over 80% of the world's rough diamonds passed through De Beers,[58] but in the period 2001–2009 the figure has decreased to around 45%.[59] De Beers sold off the vast majority of its diamond stockpile in the late 1990s – early 2000s[60]and the remainder largely represents working stock (diamonds that are being sorted before sale).[61] This was well documented in the press[62] but remains little known to the general public. As a part of reducing its influence, De Beers withdrew from purchasing diamonds on the open market in 1999 and ceased, at the end of 2008, purchasing Russian diamonds mined by the largest Russian diamond company Alrosa.[63] Alrosa had to suspend their sales in October 2008 due to the global energy crisis and was expected to resume them in late 2009.[64] Apart from Alrosa, other important diamond mining companies include BHP Billiton, which is the world's largest mining company;[65] Rio Tinto Group, the owner of Argyle (100%), Diavik (60%), and Murowa (78%) diamond mines;[66] and Petra Diamonds, the owner of several major diamond mines in Africa. Further down the supply chain, members of The World Federation of Diamond Bourses (WFDB) act as a medium for wholesale diamond exchange, trading both polished and rough diamonds. The WFDB consists of independent diamond bourses in major cutting centers such as Tel Aviv, Antwerp, Johannesburg and other cities across the USA, Europe and Asia.[19] In 2000, the WFDB and The International Diamond Manufacturers Association established the World Diamond Council to prevent the trading of diamonds used to fund war and inhumane acts. WFDB's additional activities include sponsoring the World Diamond Congress every two years, as well as the establishment of theInternational Diamond Council (IDC) to oversee diamond grading. Once purchased by Sightholders (which is a trademark term referring to the companies that have a three-year supply contract with DTC), diamonds are cut and polished in preparation for sale as gemstones ('industrial' stones are regarded as a by-product of the gemstone market; they are used for abrasives). The cutting and polishing of rough diamonds is a specialized skill that is concentrated in a limited number of locations worldwide. Traditional diamond cutting centers are Antwerp, Amsterdam, Johannesburg, New York City, and Tel Aviv. Recently, diamond cutting centers have been established in China, India, Thailand, Namibia and Botswana. Cutting centers with lower cost of labor, notably Surat in Gujarat, India, handle a larger number of smaller carat diamonds, while smaller quantities of larger or more valuable diamonds are more likely to be handled in Europe or North America. The recent expansion of this industry in India, employing low cost labor, has allowed smaller diamonds to be prepared as gems in greater quantities than was previously economically feasible. Diamonds which have been prepared as gemstones are sold on diamond exchanges called bourses. There are 26 registered diamond bourses in the world. Bourses are the final tightly controlled step in the diamond supply chain; wholesalers and even retailers are able to buy relatively small lots of diamonds at the bourses, after which they are prepared for final sale to the consumer. Diamonds can be sold already set in jewelry, or sold unset ("loose"). According to the Rio Tinto Group, in 2002 the diamonds produced and released to the market were valued at US$9 billion as rough diamonds, US$14 billion after being cut and polished, US$28 billion in wholesale diamond jewelry, and US$57 billion in retail sales.Marketing The image of diamond as a valuable commodity has been preserved through clever marketing campaigns. In particular, the De Beers diamond advertising campaign is acknowledged as one of the most successful and innovative campaigns in history. N. W. Ayer & Son, the advertising firm retained by De Beers in the mid-20th century, succeeded in reviving the American diamond market and opened up new markets, even in countries where no diamond tradition had existed before. N. W. Ayer's multifaceted marketing campaign included product placement, advertising the diamond itself rather than the De Beers brand, and building associations with celebrities and royalty. This coordinated campaign has lasted decades and continues today; it is perhaps best captured by the slogan "a diamond is forever".[7] Another example of successful diamond marketing is brown Australian diamonds. Brown-colored diamonds have always constituted a significant part of the diamond production, but were considered worthless for jewelry; they were not even assessed on the diamond colorscale, and were predominantly used for industrial purposes. The attitude has changed drastically after the development of Argyle diamond mine in Australia in 1986. As a result of an aggressive marketing campaign, brown diamonds have become acceptable gems.[70][71] The change was mostly due to the numbers: the Argyle mine, with its 35,000,000 carats (7,000 kg) of diamonds per year, makes about one-third of global production of natural diamonds;[72] 80% of Argyle diamonds are brown.[73] Cutting Main articles: Diamond cutting and Diamond cut The Darya-I-Nur Diamond—an example of unusual diamond cut and jewelry arrangement The mined rough diamonds are converted into gems through a multi-step process called "cutting". Diamonds are extremely hard, but also brittle and can be split up by a single blow. Therefore, diamond cutting is traditionally considered as a delicate procedure requiring skills, scientific knowledge, tools and experience. Its final goal is to produce a faceted jewel where the specific angles between the facets would optimize the diamond luster, that is dispersion of white light, whereas the number and area of facets would determine the weight of the final product. The weight reduction upon cutting is significant and can be of the order of 50%.[39] Several possible shapes are considered, but the final decision is often determined not only by scientific, but also practical considerations. For example the diamond might be intended for display or for wear, in a ring or a necklace, singled or surrounded by other gems of certain color and shape.[74] The most time-consuming part of the cutting is the preliminary analysis of the rough stone. It needs to address a large number of issues, bears much responsibility, and therefore can last years in case of unique diamonds. The following issues are considered: The hardness of diamond and its ability to cleave strongly depend on the crystal orientation. Therefore, the crystallographic structure of the diamond to be cut is analyzed using X-ray diffraction in order to choose the optimal cutting directions. Most diamonds contain visible non-diamond inclusions and crystal flaws. The cutter has to decide which flaws are to be removed by the cutting and which could be kept. The diamond can be split by a single, well calculated blow of a hammer to a pointed tool, which is quick, but risky. Alternatively, it can be cut with a diamond saw, which is a more reliable but tedious procedure. After initial cutting, the diamond is shaped in numerous stages of polishing. Unlike cutting, which is a responsible but quick operation, polishing removes material by gradual erosion and is extremely time consuming. The associated technique is well developed; it is considered as a routine and can be performed by technicians. After polishing, the diamond is reexamined for possible flaws, either remaining or induced by the process. Those flaws are concealed through various diamond enhancement techniques, such as repolishing, crack filling, or clever arrangement of the stone in the jewelry. Remaining non-diamond inclusions are removed through laser drilling and filling of the voids produced. Industrial uses A scalpel with synthetic diamond blade Close-up photograph of an angle grinderblade with tiny diamonds shown embedded in the metal The market for industrial-grade diamonds operates much differently from its gem-grade counterpart. Industrial diamonds are valued mostly for their hardness and heat conductivity, making many of the gemological characteristics of diamonds, such as clarity and color, irrelevant for most applications. This helps explain why 80% of mined diamonds (equal to about 135,000,000 carats (27,000 kg) annually), unsuitable for use as gemstones, are destined for industrial use. In addition to mined diamonds, synthetic diamonds found industrial applications almost immediately after their invention in the 1950s; another 570,000,000 carats (110,000 kg) of synthetic diamond is produced annually for industrial use. Approximately 90% of diamond grinding grit is currently of synthetic origin. The boundary between gem-quality diamonds and industrial diamonds is poorly defined and partly depends on market conditions (for example, if demand for polished diamonds is high, some suitable stones will be polished into low-quality or small gemstones rather than being sold for industrial use). Within the category of industrial diamonds, there is a sub-category comprising the lowest-quality, mostly opaque stones, which are known as bort.[77] Industrial use of diamonds has historically been associated with their hardness; this property makes diamond the ideal material for cutting and grinding tools. As the hardest known naturally occurring material, diamond can be used to polish, cut, or wear away any material, including other diamonds. Common industrial adaptations of this ability include diamond-tipped drill bits and saws, and the use of diamond powder as an abrasive. Less expensive industrial-grade diamonds, known as bort, with more flaws and poorer color than gems, are used for such purposes.[78]Diamond is not suitable for machining ferrous alloys at high speeds, as carbon is soluble in iron at the high temperatures created by high-speed machining, leading to greatly increased wear on diamond tools compared to alternatives.[79] Specialized applications include use in laboratories as containment for high pressure experiments(see diamond anvil cell), high-performance bearings, and limited use in specialized windows.[77]With the continuing advances being made in the production of synthetic diamonds, future applications are becoming feasible. Garnering much excitement is the possible use of diamond as a semiconductor suitable to build microchips, or the use of diamond as a heat sink[80] in electronics. Synthetics, simulants, and enhancements Synthetics Main article: Synthetic diamond Synthetic diamonds of various colors grown by the high-pressure high-temperature technique Synthetic diamonds are diamonds manufactured in a laboratory, as opposed to diamonds mined from the Earth. The gemological and industrial uses of diamond have created a large demand for rough stones. This demand has been satisfied in large part by synthetic diamonds, which have been manufactured by various processes for more than half a century. However, in recent years it has become possible to produce gem-quality synthetic diamonds of significant size.[32] The majority of commercially available synthetic diamonds are yellow and are produced by so called High Pressure High Temperature (HPHT) processes. The yellow color is caused by nitrogen impurities. Other colors may also be reproduced such as blue, green or pink, which are a result of the addition of boron or from irradiation after synthesis. Colorless gem cut from diamond grown by chemical vapor deposition Another popular method of growing synthetic diamond is chemical vapor deposition (CVD). The growth occurs under low pressure (below atmospheric pressure). It involves feeding a mixture of gases (typically 1 to 99 methane to hydrogen) into a chamber and splitting them to chemically active radicals in a plasma ignited by microwaves, hot filament, arc discharge, welding torch orlaser. This method is mostly used for coatings, but can also produce single crystals several millimeters in size (see picture). At present, the annual production of gem quality synthetic diamonds is only a few thousand carats, whereas the total production of natural diamonds is around 120,000,000 carats (24,000 kg). Despite this fact, a purchaser is more likely to encounter a synthetic when looking for a fancy-colored diamond because nearly all synthetic diamonds are fancy-colored, while only 0.01% of natural diamonds are. Simulants Main article: Diamond simulant Gem-cut synthetic silicon carbide set in a ring A diamond simulant is defined as a non-diamond material that is used to simulate the appearance of a diamond. Diamond-simulant gems are often referred to as diamante. The most familiar diamond simulant to most consumers is cubic zirconia. The popular gemstone moissanite (silicon carbide) is often treated as a diamond simulant, although it is a gemstone in its own right. While moissanite looks similar to diamond, its main disadvantage as a diamond simulant is that cubic zirconia is far cheaper and arguably equally convincing. Both cubic zirconia and moissanite are produced synthetically.Enhancements Diamond enhancements are specific treatments performed on natural or synthetic diamonds (usually those already cut and polished into a gem), which are designed to better the gemological characteristics of the stone in one or more ways. These include laser drilling to remove inclusions, application of sealants to fill cracks, treatments to improve a white diamond's color grade, and treatments to give fancy color to a white diamond. Coatings are increasingly used to give a diamond simulant such as cubic zirconia a more "diamond-like" appearance. One such substance isdiamond-like carbon—an amorphous carbonaceous material that has some physical properties similar to those of the diamond. Advertising suggests that such a coating would transfer some of these diamond-like properties to the coated stone, hence enhancing the diamond simulant. Techniques such as Raman spectroscopy should easily identify such a treatment. Identification Early diamond identification tests included a scratch test relying on the superior hardness of diamond. This test is destructive, as a diamond can scratch diamond, and is rarely used nowadays. Instead, diamond identification relies on its superior thermal conductivity. Electronic thermal probes are widely used in the gemological centers to separate diamonds from their imitations. These probes consist of a pair of battery-powered thermistors mounted in a fine copper tip. One thermistor functions as a 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. This test takes about 2–3 seconds. Whereas the thermal probe can separate diamonds from most of their simulants, distinguishing between various types of diamond, for example synthetic or natural, irradiated or non-irradiated, etc., requires more advanced, optical techniques. Those techniques are also used for some diamonds simulants, such as silicon carbide, which pass the thermal conductivity test. Optical techniques can distinguish between natural diamonds and synthetic diamonds. They can also identify the vast majority of treated natural diamonds. "Perfect" crystals (at the atomic lattice level) have never been found, so both natural and synthetic diamonds always possess characteristic imperfections, arising from the circumstances of their crystal growth, that allow them to be distinguished from each other. Laboratories use techniques such as spectroscopy, microscopy and luminescence under shortwave ultraviolet light to determine a diamond's origin. They also use specially made instruments to aid them in the identification process. Two screening instruments are theDiamondSure and the DiamondView, both produced by the DTC and marketed by the GIA. Several methods for identifying synthetic diamonds can be performed, depending on the method of production and the color of the diamond. CVD diamonds can usually be identified by an orange fluorescence. D-J colored diamonds can be screened through the Swiss Gemmological Institute's Diamond Spotter. Stones in the D-Z color range can be examined through the DiamondSure UV/visible spectrometer, a tool developed by De Beers. Similarly, natural diamonds usually have minor imperfections and flaws, such as inclusions of foreign material, that are not seen in synthetic diamonds. List of diamonds A number of large or extraordinary diamonds have gained fame, both as exquisite examples of the beautiful nature of diamonds, and because of the famous people who wore, bought, and sold them. A partial list of famous diamonds in history follows. Darya-ye Noor Tiffany Yellow Diamond Koh-i-Noor (glass replica) Name Uncut Weight Cut Weight Description Akbar Shah 116 71.7 an Indian diamond with a roughly pear-shaped outline and random faceting, including two Arabic inscriptions, the first reading "Shah Akbar, the Grand King, 1028 A.H." (the letters mean Anno Hegirae). The second inscription read "To the Lord of Two Worlds, 1039 A.H.Shah Jehan". The diamond was reportedly part of the original Peacock Throne. Purchased in 1886 in Istanbul by London merchant George Blogg, who re-cut it from 116 carats (23 g) to a pear-shape of 71.70 carats (14.34 g), thus destroying the historic inscriptions. Blogg was the last known owner and the stone's whereabouts are presently unknown. Allnatt Diamond 101.29 a 101.29-carat (20.26 g) antique cushion-shaped brilliant fancy vivid yellow diamond. Agra Diamond 28 antique cushion-shaped stellar brilliant, 28 carats (5.6 g). Amsterdam Diamond 33.74 a 33.74 carat (6.748 g) pear-shaped black diamond which sold for $352,000 in 2001. Archduke JosephDiamond 78.54 76.45 antique cushion-shaped brilliant, originally weighing 78.54 carats (15.71 g), purchased by Molina Jewelers of Arizona sometime in the late-1990s and slightly re-cut to 76.45 carats (15.29 g) to improve clarity and symmetry. D color, Internally Flawless. Ashberg Diamond 102.48 102.48 carats (20.50 g). Aurora Butterfly of Peace a display of 240 fancy-colored diamonds. Aurora Pyramid of Hope a display of 296 diamonds of natural colors. Beau Sancy 34 a 34-carat (6.8 g) diamond not to be confused with the Sancy. Black Orlov 67.5 a 67.50-carat (13.50 g) cushion-cut black diamond, also called the Eye of Brahma Diamond. Blue Heart Diamond 30.82 30.82-carat (6.16 g) heart brilliant. Part of the Smithsonian collection. Briolette of IndiaDiamond 90.38 90.38 carats (18.08 g) - possibly the oldest diamond on record. Centenary Diamond 273.85 273.85 carats (54.77 g), modified heart-shaped brilliant, the world's largest colorless (grade D), flawless diamond. Chloe Diamond largest round brilliant-cut diamond ever put on auction. Sold on November 14, 2007 at Sotheby's in Geneva to Georges Marciano of theGuess clothing line for $16.2 million, the second-highest price ever paid for a diamond on auction. Took 2 years to cut. Cross of Asia 200 142 discovered in 1902 in South Africa as a 280-carat (56 g) crystal. At first diamond was cut to 142 carats (28 g), and next the cut was three times changed to 112 carats (22 g), a cushion-cut of 109.28 carats (the weight Lawrence Copeland's "Diamonds - Famous, Notable and Unique" lists it at) measuring 1⅛ × ⅞ × ⅝ inches, and finally into a radiant-cut gem of 79.12 carats (15.82 g) to eliminate all flaws. It is Fancy Yellow and Internally Flawless.[1] Cullinan Diamond 3106.75 530.2 the largest rough gem-quality diamond ever found at 3106.75 carats (621.35 g). It was cut into 105 diamonds including the Cullinan I or the Great Star of Africa, 530.2 carats (106.04 g), and the Cullinan II or the Lesser Star of Africa, 317.4 carats (63.48 g), both of which are now part of the British Crown Jewels. Cullinan Heritage diamond set the record for the highest price ever paid for a rough diamond in February 2010 when it was sold for $35.3m (£23m) to a Hong Kong jeweller. Petra Diamonds mined the stone in 2009 at their Cullinan Diamond Mine (formerly the Premier Mine) in South Africa.[2] Darya-ye Noor Diamond 182 the largest pink diamond in the world, about 182 carats (36 g), part ofIranian Crown Jewels. Its exact weight isn't known and 186 carats (37 g) is an estimate. Deepdene 104.52 widely considered to be the largest artificially irradiated diamond in the world, at 104.52 carats (20.90 g). De Young Red Diamond 5.03 weighing 5.03 carats (1.01 g), the third-largest known red diamond, was bought in a flea market on a hatpin by Sidney deYoung a prominent Boston estate jewelry merchant. It was donated by him to theSmithsonian Institution National Museum of Natural History. Dresden Green Diamond 41 41-carat (8.2 g) antique pear-shaped brilliant - its color is the result of natural irradiation Dresden White Diamond 47 47-carat (9.4 g) antique oval brilliant, near-colorless Dresden Yellow Diamond 38 38-carat (7.6 g) antique round cut Earth Star Diamond 111.59 a 111.59-carat (22.32 g) pear-shaped diamond with a strong coffee-like brown color. Eureka Diamond 21.25 10.73 the first diamond found in South Africa, a yellow-brown 21.25-carat (4.25 g) stone (before cutting) resulting in a finished diamond 10.73 carats (2.15 g) Empress Eugenie Diamond 52 52-carat (10 g) antique pear-shaped brilliant with an odd, random facet pattern Excelsior Diamond 970 68 the largest known diamond in the world prior to the Cullinan at 970 carats (190 g), it was later cut into 10 pieces of various sizes (13–68 carats) Florentine Diamond 137.27 a lost diamond, light yellow with a weight of 137.27 carats (27.45 g). Golden Eye Diamond 43.5 a world's largest, flawless, 'perfect-cut' Canary Yellow diamond (43.5 carats). Golden Jubilee Diamond 545.67 the largest faceted diamond ever cut at 545.67 carats (109.13 g) Graff Blue Diamond Great Chrysanthemum Diamond 104.15 104.15 carats (20.83 g) Great Mogul Diamond 280 fabled 280-carat (56 g) mogul-cut diamond, now lost, although presumed by historians to have been re-cut as the Orlov. Gruosi Diamond 115.34 a heart-shaped black diamond, weighing 115.34 carats (23.07 g). Heart of Eternity Diamond 27.64 perhaps the largest fancy vivid blue, weighing 27.64 carats (5.53 g). Hope Diamond 45.52 45.52 carats (9.10 g), is a Fancy Dark Grayish-Blue diamond and supposedly cursed. Almost certainly cut from the French Blue Diamond. Hortensia Diamond peach color, formerly part of the French Crown Jewels. Displayed in theLouvre. Idol's Eye 70.21 70.21 carats[3] Incomparable Diamond 890 407.48 a brownish-yellow diamond of 407.48 carats (81.496 g) cut from an 890 carat (178 g) rough diamond of the same name - it appeared on eBay in 2002. Internally Flawless clarity. Jacob Diamond 184.5 weighing 184.5 carats (36.90 g) also known as Imperial Diamond &Victoria Diamond. Jones Diamond 34.48 weighing 34.48 carats (6.90 g), found in West Virginia by the Jones family. Jubilee Diamond 245.3 originally known as the Reitz Diamond; perhaps the sixth-largest in the world at 245.35 carats (49.07 g). Kazanjian Red Diamond 5.05 a 5.05-carat (1.01 g) Emerald-cut red diamond formerly known simply as "Red Diamond". It was cut from a 35-carat (7.0 g) piece of boart discovered near Lichtenburg, South Africa. It reappeared in 2007 after a 37-year absence from sight, and was purchased by Kazanjian Brothers Inc. Kimberley Diamond 55.09 55.09 carats[4] Koh-i-Noor 105. a 105.6 carat (21.6 g) white of Indian origin, with a long and turbulent history and a good deal of legend surrounding it. After belonging to various Mughal and Persian rulers, it was taken away from theMaharaja Duleep Singh of Lahore and was presented to Queen Victoriaduring the British Raj, and is now part of the Crown of Queen Elizabeththe Queen Mother. Lesotho Brown 601 71.73 was a stone originally 601 carats (120 g) with the largest stone 71.73 carats (14.35 g) after cutting. Lesotho Promise 603 75 is the 15th-largest diamond, the tenth-largest white diamond, and the largest diamond to be found in 13 years. The original stone was 603 carats (121 g), although the largest diamond after the cutting was 75 carats (15 g). Millennium Star 203.04 at 203.04 carats (40.61 g) is the second-largest colorless (grade D),flawless diamond. Moon of Baroda 24.04 24.04 carats (4.81 g) Moussaieff Red Diamond 5.11 the largest known Fancy Red, at 5.11 carats (1.02 g). Mouna Diamond 112.53 112.53 carats (22.51 g), Fancy Intense Yellow cushion-shaped brilliant.[5] Nassak Diamond 43.38 43.38 carats (8.68 g) Nepal Diamond 79.41 79.41 carats (15.88 g), fine quality antique pear-shaped brilliant, sold byHarry Winston to private collector in 1961. Thought to have originated from the Golconda Mines.[6] Nizam Diamond 340 reportedly 340 carats (68 g). Nur-Ul-Ain Diamond 60 around 60 carats (12 g) and part of the Iranian crown jewels. Ocean Dream Diamond 5.51 the only known natural Fancy Deep Blue-Green, and weighs 5.51 carats (1.10 g). Oppenheimer Diamond 253.7 one of the largest gem-quality uncut diamonds in the world, at 253.7 carats (50.7 g). Orlov 190 an Indian mogul cut rumored to have served as the eye of a Hindu statue, and currently is part of the Kremlin diamond fund, weighing approximately 190 carats (38 g). Paragon 137.82 weighs 137.82 carats.[7] Polar Star Diamond 41.28 a colorless cushion-shaped stellar brilliant diamond weighing 41.28 carats (8.26 g). Porter Rhodes Diamond 54 a colorless 54-carat (11 g) Asscher-cut stone.[8] Portuguese Diamond 127 127-carat (25 g) antique emerald cut with a pale yellow body color and very strong blue fluorescence. Part of the Smithsonian's collection. Premier Rose Diamond 137.0 137.02-carat (27.4 g) stone cut from a 353.9-carat (70.8 g) rough gem of the same name Pumpkin Diamond 5.54 perhaps the largest fancy vivid orange diamond (5.54 carats), modified cushion-shaped brilliant. Red Cross Diamond 205.07 205.07 carats (41.01 g), yellow, cushion-shaped stellar brilliant cut.[9] Regent Diamond 140.64 weights 140.64 carats (28.13 g), is cushion-shaped stellar brilliant cut, formerly belonging to Louis XV, Louis XVI, and Napoleon Bonaparte, it now resides in the Louvre. Sancy 55.23 a shield-shaped pale yellow diamond currently in the Louvre, weighing 55.23 carats (11.05 g). Shah Diamond 88.7 very old yellow diamond (found approximately in 1450 in India) currently housed in the Diamond Fund in Kremlin, weighing 88.7 carats (17.7 g). Spirit of de Grisogono Diamond 312 312 carats (62 g), the world's largest cut black diamond. Spoonmaker's Diamond 86 circa 86-carat (17 g) diamond housed in Topkapı Palace in Istanbul. Star of Arkansas Star of the East 95 a 95-carat (19 g) stone once owned by Evalyn Walsh McLean ofWashington DC, who also owned the Hope Diamond. Star of Sierra Leone 968.9 53.96 cut into smaller pieces, the largest of which is 53.96 carats (10.79 g). Star of South Africa 83.5 47.69 also known as the Dudley Diamond. This must not be confused with theStar of Africa. The Star of South Africa was the initial name given to this diamond, when it was purchased as an 83.5-carat (16.7 g) rough diamond. The diamond is a D-color, pear-shaped stellar brilliant cut stone, weighing 47.69 carats (9.54 g). Star of the Season 100.10 a 100.10-carat (20.02 g) pear-shaped D-color, Internally Flawless stone. At $16,548,750 US it held the world record for the highest price paid for a diamond at auction until the sale of the Wittelsbach in 2008. Star of the South 128.48 Steinmetz Pink Diamond 59.60 modified oval brilliant cut (step cut crown, brilliant pavilion), largest known fancy vivid pink, at 59.60 carats (11.92 g). Strawn-Wagner Diamond 3.03 1.09 the only diamond ever to receive a "perfect" 0/0/0 rating from theAmerican Gem Society, weighing 3.03 carats (0.61 g) rough and 1.09 carats (0.22 g) cut. On exhibit at Crater of Diamonds State Park in Arkansas, where it was found in 1990. Taylor-Burton Diamond 68 purchased by Richard Burton for his wife Elizabeth Taylor, weighing 68 carats (14 g). Tereschenko 42 42-carat (8.4 g) antique pear brilliant cut. Tiffany Yellow Diamond 128.54 antique modified cushion-shaped stellar brilliant cut, on display atTiffany & Co.'s New York City store. It weighs 128.54 carats (25.71 g). Uncle Sam 40.23 the largest discovered in the US, emerald-cut, M color (pale brown), VVS2 clarity, weighing 40.23 carats (8.05 g). Unnamed 10-carat Fancy Intense Yellow-Green Diamond 10.22 10.22-carat (2.04 g) The largest Fancy Intense yellow-green diamond known.[10] Vargas diamond Wittelsbach-Graff Diamond 35.56 35.56 carats (7.11 g), Fancy Deep Grayish Blue, antique oval stellar brilliant cut - was recut! Sold at Christie's, London, December 10, 2008 for $23.4 million to Lawrence Graff, currently the highest price ever paid for a diamond at auction. In mineralogy, diamond (from the ancient Greek αδάμας – adámas "unbreakable") is anallotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bonding between its atoms. In particular, diamond has the highest hardnessand thermal conductivity of any bulk material. Those properties determine the major industrial application of diamond in cutting and polishing tools. Diamond has remarkable optical characteristics. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron and nitrogen. Combined with wide transparency, this results in the clear, colorless appearance of most natural diamonds. Small amounts of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown (lattice defects), green, purple, pink, orange or red. Diamond also has relatively high optical dispersion, that is ability to disperse light of different colors, which results in its characteristic luster. Excellent optical and mechanical properties, combined with efficient marketing, make diamond the most popular gemstone. Most natural diamonds are formed at high-pressure high-temperature conditions existing at depths of 140 to 190 kilometers (87 to 120 mi) in the Earth mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth). Diamonds are brought close to the Earth surface through deep volcanic eruptions by a magma, which cools into igneous rocks known as kimberlitesand lamproites. Diamonds can also be produced synthetically in a high-pressure high-temperature process which approximately simulates the conditions in the Earth mantle. An alternative, and completely different growth technique is chemical vapor deposition (CVD). Several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. Specialgemological techniques have been specially developed to distinguish natural and synthetic diamonds and diamond simulants. There are four main criteria used to describe the quality of a diamond, and they are generally referred to as the Four C's: Color, Clarity, Cut, and Carat .One might argue that the most important "C " of all is actually a "B", Beauty. Although the independent gemological labs we use are renowned in the trade, the most accurate and detailed description in the world is only a poor attempt to put into words how beautiful a diamond can be. In addition to being familiar with the four C's it is also important to make sure that the diamond you are purchasing has been certified by one of the top independent gem laboratories. The two most widely trusted labs among diamond professionals are the Gemological Institute of America (GIA) and the European Gemology Laboratory (EGL). These reports will describe the four C's for you in minute technical detail. COLOR: A diamond’s color is graded on an alphabetical scale from D-Z to describe how much or how little color a diamond possesses. With very few exceptions, diamonds that are graded as colorless are considered to be the most valuable. Truly colorless stones, graded D, are extremely rare and very valuable.D-F: Colorless, perfect or almost perfect color. G-J: Near colorless, good to very good color. This diamond may “face up” colorless when mounted. K-M: Light but noticeable yellow or brown tint. May “face up” near colorless when mounted, especially when mounted in yellow gold. While many diamonds appear colorless, or white, they may actually have subtle yellow or brown tones that can be detected when comparing diamonds side by side. Diamonds were formed under intense heat and pressure, and traces of other elements may have been incorporated into their atomic structure accounting for the variances in color. A single change in color grade can significantly affect a diamond’s value. Although the presence of color makes a diamond less rare and valuable, some diamonds come out of the ground in vivid "fancy" colors--well-defined reds, blues, pinks, greens, and bright yellows. These are highly prized and extremely rare.

CLARITY: Clarity is an indication of a diamond's purity. It is the term used to describe quite literally the clearness or lack of flaws in a diamond. All diamonds have some, naturally occurring marks in them, which may or may not be visible to the naked eye. These are known as imperfections or inclusions. In all diamonds, except the most rare, tiny traces of minerals, gasses, or other elements were trapped inside during the crystallization process. These are called inclusions, but are more like birthmarks. They are called this because they are “included” in the diamond! They may look like tiny crystals, clouds, or feathers and they're what make each diamond different and unique. Many of these birthmarks are not visible to the naked eye. In fact, it is very rare to find a diamond that is completely clean to the expert eye using magnification. The clarity of a diamond is graded by how many, how big and how visible the inclusions are. The fewer and smaller the inclusions, the more rare and valuable the diamond. Less than 1% of all diamonds ever found have had no inclusions and can be called internally flawless (IF).The following are abbreviations for terms that are used world wide to describe the clarity of a diamond: IF,VVS1,VVS2: Internally flawless or near flawless. Impossible to extremely difficult to find any inclusions, even under 10x magnification. IF is Internally Flawless, and VVS1 and VVS2 are “Very, very slightly included”. VS1,VS2: 100% clean to the naked eye, and moderately difficult to very difficult to find inclusions with 10x magnification. VS1 and VS2 are “Very slightly included”. SI1, SI2, SI3: Should be completely to almost completely clear to the naked eye (eye clean) when viewed from the top. Fairly easy to find imperfections with 10x magnification. SI diamonds are “Slightly included”. I1, I2, I3: Borderline “eye clean” to fairly easy to find imperfections with the naked eye. Very easy to find imperfections with 10x magnification. I1 through I3 diamonds are “Included”.

CUT: This is one of the most important of all characteristics, and among the hardest to judge. All other factors being equal, a poorly cut diamond can be worth less than half the value of a well “made” stone. The proportions of a stone as well as its polish and precision of faceting determine how much of the diamond’s potential fire and beauty may be released.Diamond cutters are paid to retain the maximum weight from rough stones. You will find poorly cut diamonds such as overly long or fat Marquises, extremely deep Heart Shapes and Emerald Cuts, and Ovals and Pear Shapes with big shoulders, or overly deep or out of shape Rounds. A poorly made stone tends to result in a higher yield (less waste) from the rough while a better made diamond “wastes” more of the rough. A well cut round diamond typically weighs only about 40% or less of the original weight of the piece of rough the cutter started with. This is why better cut diamonds and near ideal cut stones command a premium. The way a diamond is cut will most certainly influence its sparkle, fire and brilliance, as well as its perceived size and even, to some degree its apparent color. In order to maximize the diamond’s brilliance it must be cut in a geometrically precise manner. This means properly aligning the facets so light will enter the diamond and reflect back through the large top facet, or table of the diamond. Shown below is an example of how a finely cut diamond will reflect light. Symmetry, polish, and faceting are the most noticeable features of cut, but also important are percentages for depth, height and angles. Light should enter and exit a diamond through the top facets. A cut that is too shallow or too deep reflects it through the bottom facets, and lets the light “leak” out of the bottom or side of the gem.

CARAT WEIGHT: The standard unit of measure for diamonds and other gemstones is the carat. One carat is equal to 1/5 of a gram, or 1/142 of an ounce. The carat is also referred to as containing 100 “points”. Therefore, a 50-point diamond weighs ½ carat, a 25-point diamond weighs ¼ carat, and so on.The price per carat of diamonds can at times increase exponentially with size, due to the rarity of larger gemstones. A one-carat diamond typically costs 3.5 to 4 times what an equivalent ½ carat costs, and the same goes for subsequent increases in size.