About Diamonds | OGI Systems

Diamond

A diamond is a hard mineral made of clean carbon. The diamond
The diamond crystal belongs to the cube system and appears in
Most of the diamonds are invisible to the inexperienced and
For every 10,000 diamonds produced in the world, one colored
The colored diamonds receive their special colors thanks to
The prices of rough diamonds are determined by the various
The division into the four Cs was developed in the late 1930s by
The diamond is the hardest and most brilliant mineral: its level
The quality of most of the diamonds produced worldwide can not be
Industrial diamonds are called Boart or Carbonado. Some of them

Diamond structure

Like graphite, the diamond is made up of a single
The diamond is an atomic lattice. The carbon atoms in the crystals

Natural Diamonds

The diamond was created at depths of 200-250 kilometers at
These conditions exist beneath the Earth's crust under the most
In a slow cooling process the carbon solidified and crystallized
The diamonds made their way to the surface of the earth using rocks
Measurement

There is no uniform and absolute international standard for
Clarity

The level of clarity of the diamond, which is referred to in
FL (no inclusions and imperfections) - A diamond with no inclusions IF (no inclusions) - a diamond with no inclusions but only visible VVS1 (very very small inclusions) tiny inclusions that even a VVS2 (very very small inclusions) - tiny inclusions that even a VS1 (very small inclusions) - very small inclusions, some of which VS2 (very small inclusions) - very small inclusions, some of which SI1 (inclusions are visible) - small inclusions that a specialist SI2 (inclusions are visible) - small inclusions that a specialist I1 (many inclusions) - inclusions that are easily visible at
Level 1.
I2 (many inclusions) - inclusions that are easily visible at I3 (many inclusions) - inclusions that are easily visible at

The color of the diamond
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It is customary to divide the diamonds into two main groups -
The usual color group
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The usual color group includes diamonds from the clear, colorless,
It is important to note that the differences between the level of
Special color group
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This group includes the strong yellows and the special colors
The colors of colored diamonds, or their commercial name Fancy color
The color of the diamond: There is a table of 27 different shades to

Brightness / Darkness Alongside the color depth of the ---------------------------------------------------------------- each colored diamond will be graded according to its brightness or
Fancy Light
Fancy
Fancy Intense
Fancy Dark
Fancy Deep
Fancy Vivid
Another variable that influences diamond color determination is the
The inner color of the colored diamond will not necessarily be
Fluorescent diamond
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Another index that affects the price of a diamond and its perceived
Diamond polishing
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The hustle is the desktop of the plank. The mulch is composed of the
Today, before the start of the polishing work, computer software is
In the Fancy Color field, the work of the diamond is still
In the past, the State of Israel was one of the most important
White diamond polishing
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The quality of diamond polishing has a direct impact on its
As with the other diamond characteristics, there is no uniform
Polishing of colored diamonds
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In contrast to white diamonds where the goal of polishing is to

Industry

The diamond industry can be separated into two distinct

Gem-grade diamonds

A large trade in gem-grade diamonds exists. Although most gem-grade
The production and distribution of diamonds is largely consolidated
The De Beers company, as the world's largest diamond mining company,
As a part of reducing its influence, De Beers withdrew from
Further down the supply chain, members of The World Federation of
Once purchased by Sightholders (which is a trademark term referring
Diamonds prepared as gemstones are sold on diamond exchanges called

Cutting

Mined rough diamonds are converted into gems through a multi-step
The most time-consuming part of the cutting is the preliminary
The hardness of diamond and its ability to cleave strongly depend on Most diamonds contain visible non-diamond inclusions and crystal The diamond can be split by a single, well calculated blow of a After initial cutting, the diamond is shaped in numerous stages of

Industrial-grade
Industrial diamonds are valued mostly for their hardness and thermal
The boundary between gem-quality diamonds and industrial diamonds is
Industrial use of diamonds has historically been associated with
Specialized applications include use in laboratories as containment

Mining

Approximately 130,000,000 carats (26,000 kg) of diamonds are mined
Roughly 49% of diamonds originate from Central and Southern Africa,

Only a very small fraction of the diamond ore consists of actual crystallized hundreds of millions of years ago into a crystalline crystal at a pressure of about 60,000 atmospheres at a temperature of about 1200 to 1600 degrees Celsius at a depth of about 200-250 kilometers below the earth's surface. The diamonds were made of two types of rocks: ecological rock and peridotite rock. With the movements of the tectonic plates and the harsh convection actions, the fluid of the trend is sometimes created to the surface, bearing diamond crystals inside. When the incursions burst into the surface, the erosion dissolved the penetration rock, which is soft relative to the diamond. The diamonds were washed, sank into streams and sometimes even reached the sea. These are the secondary mining sources. The penetration that did not reach the surface becomes an initial mining source, which is found in kimberlite or mphroite rocks.
nature as a octagon or cube. The diamond is one of the alotropic of carbon. Another well known alotrop is graphite.
colorless. In their gemological grading they are included in the usual color group, even if they have a very low level of yellow and even light brown tones. Some levels of color intensity are included in the Fancy Color Diamonds.
diamond is found, which may be yellowish or brown, which is the most common. The more rare colors - green, blue, pink, orange, black, and the rarer - red, appear very low, up to one million.
foreign atoms caught in them during the crystallization of the diamond in nature or by structural deformations in the diamond lattice: yellow, orange and brown are obtained by nitrogen atoms that penetrated the diamond during its crystallization, blue is obtained from the penetration of the boron, , The addition of graphite produces black diamonds, and structural deformations in the diamond lattice are responsible for the pink and red colors.
classification categories relating to shape, size, color and cleanliness. The price of polished diamonds is also determined by the quality of the polishing. The polished diamond rating is known as the four Cs - four words that begin with the English letter C and define the characteristics of the polished diamond as they appear in the gemological grading certificates - Carat, Color, Clarity, Cut - And finish level).
the founder of the leading American gemological laboratory, Shifley.
of difficulty is 10 Mohs Scale - the highest degree of difficulty in nature. The unique weight of the diamond 3.52. The coefficient of breaking its rays of light - 2.417 creates the glow and brilliance, which give the diamond its special beauty after its polishing.
processed as gem quality, either because of inclusions or severe structural problems. Over the years, industrial diamonds accounted for about 80% of the natural diamond production. In 1967, the diamond conglomerate De Beers, which was the exclusive channel for the supply of rough diamonds at the time, split the category of industrial diamonds, creating another category - Near Gem Quality. According to the new division: about 20% are defined as decorative diamonds, about 45% are defined as semi-decorative diamonds, and about 35% are defined as industrial diamonds. The motive for De Beers' move was the decline in the profitability of industrial diamonds following the advent of the synthetic diamond, which is preferable to the natural diamond industry. At the same time, the De Beers Corporation discovered India as the land of unlimited possibilities for making industrial rough a quality of almost ornamental because of cheap wages, which enabled the processing of large quantities of small diamonds at low quality.
are shredded and used as a diamond polishing powder (because of the hardness of a diamond, only a diamond can be polished), and some are routed to the industry: drilled heads for rock drilling, concrete, glass lens polishing, dental drills, Today, there are machines for artificially producing diamonds, although it is not possible to produce white diamonds. These diamonds are used mainly by IAI. In addition, there are diamond cutting and polishing machines that enable the cutting of rough diamonds in the most optimal way, while demonstrating the diamond's truth, so that the number of diamonds with the highest degree of cleanliness and the optimal and most profitable sizes will be produced.
element, carbon, but the crystal forms of these two materials are very different. The phenomenon is called "polymorphism" and is the property of a permanent chemical compound that appears in several crystalline forms.
are arranged so that each atom creates covalent bonds with four other atoms nearby, so that around each atom a structure of four carbon atoms is arranged in the vertices of a tetrahedron. This structure is extremely stable (low energy level), because the electron pairs involved in the perfect covalent bonds are as far apart as possible. The stability of the structure is what gives the diamond its strength and hardness.
temperatures of about 1,000 to 1,200 degrees Celsius at a pressure of about 60,000 atmospheres.
ancient continents, such as in South Africa, Siberia, Western Canada or Brazil. Apparently the diamonds are made from coal-rich compounds.
into the diamond, absorbing substances from its environment, which would determine its color, and would be one of the factors determining its level of cleanliness.
of various kinds, mainly kimberlite rocks (named after Kimberley, which was built near the first diamond mine built in South Africa in the 1870s), and Salafi Lamproit. The kimberlite, a relatively soft rock that rises faster than the rocks around it, bursts from a depth of 150-200 km in the form of a carrot, a dike or a sill, in order to locate the kimberlite rocks, usually covered with layers of soil and rock, About 10% of the world's kimberlite rocks contain diamonds, and less than 1% is considered an economic kimberlite (with a commercial diamond content of both quantity and monetary value).
determining the quality of a diamond, and involves various tests, most of which are carried out by humans, and their outcome depends to a great extent on their expertise. This is one of the characteristics of the global diamond industry, which finds it very difficult to create a uniform standard for diamond valuation. Several gemological laboratories in the world are considered to be leading, documenting diamonds. The most prestigious and rigid laboratory in the world is the American Gemological Laboratory (GIA).
commercial jargon as cleanliness, refers to the defects and the roughness of the diamond - inside and on the surface of the face. The clarity of the diamond's dives will be determined by the type of the inclusions or defects, their size, location, visibility, etc. This is the hierarchical ladder used by the American laboratory GIA:
or internal or external defects visible to the eye of a gemologist is 10 times more magnified.
defects of a specialist gemologist at 10 times magnification.
specialist gemologist finds it difficult to see in 10 times magnification level 1.
specialist gemologist finds it difficult to see in 10 times magnification level 2.
will be difficult to distinguish even by a specialist gemologist at 10 times magnification level 1
will be difficult to distinguish even by a specialist gemologist at 10 times magnification level 2.
gemologist can easily distinguish by 10 times magnification level 1.
gemologist can easily distinguish by 10 times magnification level 2.
magnification 10 times and sometimes without magnification. These defects may affect the sparkle and transparency of the diamond. magnification 10 times and sometimes without magnification. These defects may affect the sparkle and transparency of the diamond. Level 2.
magnification 10 times and sometimes without magnification. These defects may affect the sparkle and transparency of the diamond. Level 3.
regular colors and special colors (colored diamonds). Each group has its own rating scale.
so-called white, to bright yellows and even light browns. The yellows are light in their various shades and are the most common in nature due to the conditions and processes that existed during the formation of diamonds. The usual color scale is marked with the letters D - Z (because at the time the ABC letters were used to mark diamonds in the commercial sector). The letter D marks a completely colorless diamond. The higher the letters, the more the color of the diamond is yellowish. The letter Z symbolizes very yellow diamonds that are not yet considered colored diamonds. For the most part, low-colored diamonds are not wanted and their prices are cheap.
diamond color and the one after or before it are so minimal that even an expert in the field can find it difficult to identify the exact color without professional accessories such as lighting, color paper and so on. The fact is intensified in cases where the diamond is already embedded in the jewel. The yellowing of the diamond begins to be visible in H-I colors, and there too, it is very light yellowish, especially in cases where there is another white diamond for comparison.
resulting from yellows, such as: blue, orange, green, pink, red, purple, dark brown and black. The special colors are created due to the penetration of foreign substances and chemical components into the diamond body when it is formed at a higher dose than the usual color diamonds, causing excessive absorption of certain colors and strong accentuation of other shades or structural deformations.
diamonds, are measured in a completely different way, with the most important criterion being the color intensity of the diamond. Determination of the color of the diamond takes into account three main parameters - tint (there are 27 different shades), brightness or dark color and depth of color.
classify the diamond. In cases where the diamond has two distinct shades, it determines the dominant shade and marks it first in the gemological certificate.
diamond
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darkness ranging from very bright to very dark. After determining the degree of brightness or darkness of the diamond color, the gemologist who evaluates the diamond will determine its color depth and the grade will range from weak to strong. After the gemologist has determined these two parameters, he will cross between them in a graph of two parameters (darkness and depth). The cross between the color depth of the diamond and its brightness / darkness will determine the color intensity on the next hierarchical ranking scale (the first is the least qualitative and the last is the most High quality):
color distribution of the diamond and its color uniformity.
exposed without proper polishing. There are diamond polishers specializing in colored diamonds and all their work is to expose the inner color of the diamond by its correct polishing.
quality is the diamond's fluorescent index. Many diamonds emit bluish light when placed under a UV bulb (which distributes ultraviolet rays). For colorless diamonds, high fluorescence is considered to create a viscosity in their appearance and therefore reduces them. For yellowish diamonds, high fluorescence is a positive thing because it whitens them. There are quite a few reviews about the use of the fluorescent index in diamond pricing and there are quite a few claims that the fluorescence in the diamond does not affect its appearance. Either way, it is the criterion that affects the price of the diamond, especially in the higher weight ranges, so be aware of it.
way the diamond sets the side to which the rough diamond is glued. The polishing work takes several hours or even days - depending on the size of the rough to polish. The polishing work is ancient and the method of polishing has not changed from the previous century. At the same time, the polishing technology has progressed immeasurably over the past 30 years.
used to read the rough and show the ideal model for polishing the diamond. In addition, there are today used automatic polishing machines for small white diamonds.
significant and unique. Therefore, despite the supporting technologies, the work of the polishing is important and decisive.
diamond polishing centers in the world. But since the 1980s, it has lost its status when most manufacturing has moved to East Asia, mainly to India and China, where wages are significantly lower.
appearance and price. A rough diamond is lifeless and does not sparkle and only its correct polishing achieves its ability to return light. In recent decades, all the round diamonds have been polished in the form of modern polishing with very clear rules for the number of diamond wigs and their proportion, a proper proportion between the diameter of the diamond and its height. The reason for the change was a technological advance that allowed for a deeper understanding of the best way to make light rays stay longer inside the diamond and thus increase the light it produces. The modern standards for diamond polishing are based largely on the development of Marcel Tolkowsky at the beginning of the 20th century.
international standard for diamond polishing, but relatively speaking it is the most scientific criterion in its nature and the differences between the various modern cutting standards are relatively small. In the gemstone certificate of the Zion diamond, the cut consists of three different parameters - polishing, polishing and symmetry.
maximize the diamond's ability to return the light, the goal of polishing colored diamonds is to maximize the color of the diamond and give it extra power. The specialty in polishing colored diamonds is special expertise and requires very high skill. In contrast to a round cut of white diamonds that maximizes the potential of the diamond, in colored diamonds, diamonds are hardly polished because this is not a form that maximizes the color of the diamond. For this reason it is customary to polish the diamond into different shapes such as drop, radiant, heart, emerald, marquise and more mainly according to current fashion and taste of the crowd. A very important consideration in determining the shape of the polished diamond is to maintain the maximum weight of the diamond after it is polished. The final consideration is, as stated, the extraction of the diamond's color ability and strength.
categories: one dealing with gem-grade diamonds and another for industrial-grade diamonds. Both markets value diamonds differently.
diamonds are sold newly polished, 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. Other important centers of diamond cutting and trading are the Antwerp diamond district in Belgium, where the International Gemological Institute is based, London, the Diamond District in New York City, the Diamond Exchange District in Tel Aviv, and Amsterdam. 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 mine that can produce between 12,500,000 and 15,000,000 carats (2,500 and 3,000 kg) of diamonds per year). Secondary alluvial diamond deposits, on the other hand, 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).
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. This makes Antwerp a de facto "world diamond capital". The city of Antwerp also hosts the Antwerpsche Diamantkring, created in 1929 to become the first and biggest diamond bourse dedicated to rough diamonds. Another important diamond center is New York City, where almost 80% of the world's diamonds are sold, including auction sales.
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 is currently the world's largest operator of diamond production facilities (mines) and distribution 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, but by 2001�2009 the figure had decreased to around 45%, and by 2013 the company's market share had further decreased to around 38% in value terms and even less by volume. De Beers sold off the vast majority of its diamond stockpile in the late 1990s � early 2000s and the remainder largely represents working stock (diamonds that are being sorted before sale). This was well documented in the press but remains little known to the general public.
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. As of January 2011, De Beers states that it only sells diamonds from the following four countries: Botswana, Namibia, South Africa and Canada. Alrosa had to suspend their sales in October 2008 due to the global energy crisis, but the company reported that it had resumed selling rough diamonds on the open market by October 2009. Apart from Alrosa, other important diamond mining companies include BHP Billiton, which is the world's largest mining company;[61] Rio Tinto Group, the owner of the Argyle (100%), Diavik (60%), and Murowa (78%) diamond mines; and Petra Diamonds, the owner of several major diamond mines in Africa.
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. 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 the International Diamond Council (IDC) to oversee diamond grading.
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.
bourses. There are 28 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.
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%. 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. Some of them may be considered as classical, such as round, pear, marquise, oval, hearts and arrows diamonds, etc. Some of them are special, produced by certain companies, for example, Phoenix, Cushion, Sole Mio diamonds, etc.
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 crystal orientation. Therefore, the crystallographic structure of the diamond to be cut is analyzed using X-ray diffraction to choose the optimal cutting directions.
flaws. The cutter has to decide which flaws are to be removed by the cutting and which could be kept.
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.
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.
diamonds

conductivity, making many of the gemological characteristics of diamonds, such as the 4 Cs, irrelevant for most applications. 80% of mined diamonds (equal to about 135,000,000 carats (27,000 kg) annually) are unsuitable for use as gemstones and are used industrially. In addition to mined diamonds, synthetic diamonds found industrial applications almost immediately after their invention in the 1950s; another 570,000,000 carats (114,000 kg) of synthetic diamond is produced annually for industrial use (in 2004; in 2014 it is 4,500,000,000 carats (900,000 kg), 90% of which is produced in China). Approximately 90% of diamond grinding grit is currently of synthetic origin.
poorly defined and partly depends on market conditions (for example, if demand for polished diamonds is high, some lower-grade 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.
their hardness, which 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 applications of this property 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. 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.
for high-pressure experiments (see diamond anvil cell), high-performance bearings, and limited use in specialized windows. With the continuing advances being made in the production of synthetic diamonds, future applications are becoming feasible. The high thermal conductivity of diamond makes it suitable as a heat sink for integrated circuits in electronics.
annually, with a total value of nearly US$9 billion, and about 100,000 kg (220,000 lb) are synthesized annually.
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.
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, the separation was done with grease belts; diamonds have a stronger tendency to stick to grease than the other minerals in the ore.

Historically, diamonds were found only in alluvial deposits in Guntur and Krishna district of the Krishna River delta in Southern India. India led the world in diamond production from the time of their discovery in approximately the 9th century BC 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. Currently, one of the most prominent Indian mines is located at Panna.

Diamond extraction from primary deposits (kimberlites and lamproites) started in the 1870s after the discovery of the Diamond Fields in South Africa. 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. 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.

In the U.S., diamonds have been found in Arkansas, Colorado, New Mexico, Wyoming, and Montana. 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. The Crater of Diamonds State Park in Arkansas is open to the public, and is the only mine in the world where members of the public can dig for diamonds.

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 the Congo. In 2005, Russia produced almost one-fifth of the global diamond output, according to the British Geological Survey. Australia boasts the richest diamantiferous pipe, with production from the Argyle diamond mine reaching peak levels of 42 metric tons per year in the 1990s. There are also commercial deposits being actively mined in the Northwest Territories of Canada and Brazil. Diamond prospectors continue to search the globe for diamond-bearing kimberlite and lamproite pipes.

Synthetics

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. It is possible to make colorless synthetic gemstones that, on a molecular level, are identical to natural stones and so visually similar that only a gemologist with special equipment can tell the difference.

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.

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 or laser. This method is mostly used for coatings, but can also produce single crystals several millimeters in size (see picture).

As of 2010, nearly all 5,000 million carats (1,000 tonnes) of synthetic diamonds produced per year are for industrial use. Around 50% of the 133 million carats of natural diamonds mined per year end up in industrial use. Mining companies' expenses average $40 to $60 per carat for natural colorless diamonds, while synthetic manufacturers' expenses average $2,500 per carat for synthetic, gem-quality colorless diamonds.[99]:79 However, 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

A diamond simulant is a non-diamond material that is used to simulate the appearance of a diamond, and may be referred to as diamante.�Cubic zirconia�is the most common. The gemstone�moissanite�(silicon carbide) can be treated as a diamond simulant, though more costly to produce than cubic zirconia. Both 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 is diamond-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 another 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.

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.Similarly, natural diamonds usually have minor imperfections and flaws, such as inclusions of foreign material, that are not seen in synthetic diamonds.

Screening devices based on diamond type detection can be used to make a distinction between diamonds that are certainly natural and diamonds that are potentially synthetic. Those potentially synthetic diamonds require more investigation in a specialized lab. Examples of commercial screening devices are Diatrue (OGI Systems ).

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