What is a diamond?

Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. At room temperature and pressure, another solid form of carbon known as graphite is the chemically stable form, but diamond almost never converts to it.

Diamond has the highest hardness and thermal conductivity of any natural material, properties that are utilized in major industrial applications such as cutting and polishing tools. Because the arrangement of atoms in diamond is extremely rigid.

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Diamond color

The Gemological Institute of America (GIA) grades diamond color on a scale of D (colorless) to Z (light yellow or brown). The color of a diamond may be affected by chemical impurities:

  • Blue diamond – boron
  • Yellow diamond – nitrogen
  • Brown diamond – defects
  • Green diamond – radiation exposure
  • Purple diamond,
  • Pink diamond,
  • Orange diamond
  • Red diamond
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What is the best color diamond?

The highest quality, a chemically pure and structurally perfect diamonds are colorles.

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How old is a diamond?

Most natural diamonds have ages between 1 billion and 3.5 billion years. Most were formed at depths between 150 and 250 kilometres (93 and 155 mi) in the Earth’s mantle, although a few have come from as deep as 800 kilometres (500 mi). Under high pressure and temperature, carbon-containing fluids dissolved minerals and replaced them with diamonds. Much more recently (tens to hundreds of million years ago), they were carried to the surface in volcanic eruptions and deposited in igneous rocks known as kimberlites and lamproites.

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Synthetic diamonds

Synthetic diamonds can be grown from high-purity carbon under high pressures and temperatures or from hydrocarbon gas by chemical vapor deposition. Imitation diamonds can also be made out of materials such as cubic zirconia and silicon carbide. Natural, synthetic and imitation diamonds are most commonly distinguished using optical techniques or thermal conductivity measurements.

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Diamond imitations – fake diamonds

A diamond simulant, diamond imitation or fake diamonds is an object or material with gemological characteristics similar to those of a diamond. Fake diamonds are distinct from synthetic diamonds, which are actual diamonds having the same material properties as natural diamonds.

A diamond simulant may be artificial, natural, or in some cases a combination thereof. While their material properties depart markedly from those of diamond, simulants have certain desired characteristics. Trained gemologists with appropriate equipment are able to distinguish natural and synthetic diamonds from all diamond simulants, primarily by visual inspection.

fake diamond

The most common diamond simulants are high-leaded glass (i.e., rhinestones) and cubic zirconia (CZ), both artificial materials. A number of other artificial materials, such as strontium titanate and synthetic rutile have been developed since the mid-1950s, but these are no longer in common use. Introduced at the end of the 20th century, the lab-grown product moissanite has gained popularity as an alternative to diamond. The high price of gem-grade diamonds, as well as significant ethical concerns of the diamond trade, have created a large demand for diamond simulants.

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Diamond color

Depending on the hue and intensity of a diamond’s coloration, a diamond’s color can either detract from or enhance its value.

diamond color scale

For example, most white diamonds are discounted in price when more yellow hue is detectable, while intense pink diamonds or blue diamonds (such as the Hope Diamond) can be dramatically more valuable. Of all colored diamonds, red diamonds are the rarest. The Aurora Pyramid of Hope displays a spectacular array of naturally colored diamonds, including red diamonds.

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Value of colored diamonds

Fancy diamonds are valued using different criteria than those used for regular diamonds. When the color is rare, the more intensely colored a diamond is, the more valuable it becomes.

Another factor that affects the value of Fancy-Colored diamonds is fashion trends. For example, pink diamonds fetched higher prices after Jennifer Lopez received a pink diamond engagement ring.

Jennifer Lopez - pink legacy

Traditional industrial use and low-grade quality has not stopped creative merchants, such as Le Vian, from marketing dark brown diamonds as so-called “chocolate diamonds”.

Fancy-colored diamonds such as the deep-blue Hope Diamond are among the most valuable and sought-after diamonds in the world. In 2009 a 7-carat (1.4 g) blue diamond fetched the then highest price per carat ever paid for a diamond when it was sold at auction for 10.5 million Swiss francs (US$9.5 million at the time) which is in excess of US$1.3 million per carat. This record was broken in 2013 when an orange diamond sold for US$35 million or US$2.4 million per carat. It was again broken in 2016 when the Oppenheimer Blue, a 14.62-carat (2.924 g) vivid blue diamond became the most expensive jewel ever sold at auction. It is the largest fancy vivid blue diamond classified by the Gemological Institute of America ever sold at auction; it sold at Christie’s in Geneva in May 2016 for US$50.6 million. The record was broken again by the pink star diamond On 3 April 2017, the Pink Star was sold at an auction in Hong Kong for US$71.2 m (553 million Hong Kong dollars including fees) to Chow Tai Fook Enterprises.(GBP 34.7m; 56.83m SFr).

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Diamond clarity

Diamond clarity is the quality of diamonds that relates to the existence and visual appearance of internal characteristics of a diamond called inclusions, and surface defects, called blemishes. Clarity is one of the four Cs of diamond grading, the others being carat, color, and cut.

Inclusions are solids, liquids, or gases that were trapped in a mineral as it formed. They may be crystals of a foreign material or even another diamond crystal, or may have produced structural imperfections, such as tiny cracks that make a diamond appear whitish or cloudy. The number, size, color, relative location, orientation, and visibility of inclusions can all affect the relative clarity of a diamond. A clarity grade is assigned based on the overall appearance of the stone under ten times magnification, which is a magnification standard for loupes used in the gem world.

Most inclusions present in gem-quality diamonds do not affect the diamonds’ performance or structural integrity and are not visible to the naked eyes. However, large clouds can affect a diamond’s ability to transmit and scatter light. Large cracks close to or breaking the surface may reduce a diamond’s resistance to fracture.

Diamonds with higher clarity grades are more valued, with the exceedingly rare “Flawless” graded diamond fetching the highest price. Minor inclusions or blemishes are useful, as they can be used as unique identifying marks analogous to fingerprints. In addition, as synthetic diamond technology improves and distinguishing between natural and synthetic diamonds becomes more difficult, inclusions or blemishes can be used as proof of natural origin.

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Diamond flaws

Diamond flaws are common. Few diamonds are perfect; most of them have inclusions or imperfections. These inclusions are also known as flaws and exist in various forms, such as exterior and interior. Inclusions are also classified in the manner in which they were formed. For example, syngenetic diamond inclusions are inclusions which were formed while a diamond formed, while epigenetic inclusions occurred after a diamond was formed.

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Carat

The carat (ct) (not to be confused with the unit of purity of gold alloys), is a unit of mass equal to 200 mg (0.00705 oz) and is used for measuring gemstones and pearls. The current definition, sometimes known as the metric carat, was adopted in 1907 at the Fourth General Conference on Weights and Measures, and soon afterwards in many countries around the world. The carat is divisible into one hundred points of two milligrams each. Other subdivisions, and slightly different mass values, have been used in the past in different locations.

In terms of diamonds, a paragon is a flawless stone of at least 100 carats (20 g).

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International carat

An ‘international carat’ of 205 milligrams was proposed in 1871 by the Syndical Chamber of Jewellers, etc., in Paris, and accepted in 1877 by the Syndical Chamber of Diamond Merchants in Paris. A metric carat of 200 milligrams – exactly one-fifth of a gram – had often been suggested, and was finally proposed by the International Committee of Weights and Measures, and accepted at the fourth sexennial General Conference of the Metric Convention held in Paris in October 1907. It was soon made compulsory by law in France, but uptake of the new carat was slower in England, where its use was allowed by the Weights and Measures (Metric System) Act of 1897.

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Diamond cut

A diamond cut is a style or design guide used when shaping a diamond for polishing such as the brilliant cut. Cut does not refer to shape (pear, oval), but the symmetry, proportioning and polish of a diamond. The cut of a diamond greatly affects a diamond’s brilliance; this means if it is cut poorly, it will be less luminous.

diamond cut

In order to best use a diamond gemstone’s material properties, a number of different diamond cuts have been developed. A diamond cut constitutes a more or less symmetrical arrangement of facets, which together modify the shape and appearance of a diamond crystal. Diamond cutters must consider several factors, such as the shape and size of the crystal, when choosing a cut.

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Diamond treatments

Diamond enhancements are specific treatments, performed on natural diamonds (usually those already cut and polished into gems), which are designed to improve the visual gemological characteristics of the diamond in one or more ways. These include clarity treatments such as laser drilling to remove black carbon inclusions, fracture filling to make small internal cracks less visible, color irradiation and annealing treatments to make yellow and brown diamonds a vibrant fancy color such as vivid yellow, blue, or pink.

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Diamond clarity and color enhancement

Clarity and color enhanced diamonds sell at lower price points when compared to similar, untreated diamonds. This is because enhanced diamonds are originally lower quality before the enhancement is performed, and therefore are priced at a substandard level. After enhancement, the diamonds may visually appear as good as their non-enhanced counterparts.

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Diamond mines

There are a limited number of commercially available diamond mines currently operating in the world, with the 50 largest mines accounting for approximately 90% of global supply.

diamond mine

Diamonds are also mined alluvially over disperse areas, where diamonds have been eroded out of the ground, deposited, and concentrated by water or weather action. There is also at least one example of a heritage diamond mine (Crater of Diamonds State Park).

Africa

Angola

  • Catoca diamond mine
  • Fucauma diamond mine
  • Luarica diamond mine

Botswana

  • Damtshaa diamond mine
  • Jwaneng diamond mine
  • Letlhakane diamond mine
  • Orapa diamond mine
  • Karowe diamond mine
  • Lerala diamond mine

South Africa

  • Baken diamond mine
  • Cullinan diamond mine (previously “Premier mine”)
  • Finsch diamond mine
  • Kimberley, Northern Cape
  • Koffiefontein mine
  • Venetia diamond mine

Others

  • Baba Diamonds Fields, Zimbabwe
  • Marange diamond fields, Zimbabwe
  • Murowa diamond mine, Zimbabwe
  • Williamson diamond mine, Tanzania
  • Letseng diamond mine, Lesotho
  • Miba, Democratic Republic of the Congo

Asia

Russia

  • Mirny GOK
  • Udachny GOK
  • Jubilee
  • Grib
  • Aikhal
  • Komsomolskaya
  • International
  • Zarnitsa mine

India

  • Kollur Mine
  • Panna

Indonesia

  • Martapura

Australia

  • Argyle diamond mine
  • Merlin diamond mine

North America

Canada

  • Diavik Diamond Mine, Northwest Territories
  • Ekati Diamond Mine, Northwest Territories
  • Jericho Diamond Mine, Nunavut
  • Snap Lake Diamond Mine, Northwest Territories
  • Victor Diamond Mine, Ontario
  • Gahcho Kue Diamond Mine Project, Northwest Territories
  • Renard Diamond Mine, Quebec
  • Stornoway

United States

  • Crater of Diamonds State Park, Arkansas (Former mine now a state park)
  • Kelsey Lake Diamond Mine, Colorado (Former mine no longer in operation)

 


Source: Wikipedia

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