Diamond color. gia diamonds
A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. However, in reality almost no gem-sized natural diamonds are absolutely perfect. The color of a diamond may be affected by chemical impurities and/or structural defects in the crystal lattice. Depending on the hue and intensity of a diamond’s coloration, a diamond’s color can either detract from or enhance its value. For example, most white diamonds are discounted in price when more yellow hue is detectable, while intense pink or blue diamonds (such as the Hope Diamond) can be dramatically more valuable. Out of all colored diamonds, red diamonds are the rarest of all. The Aurora Diamond Collection displays a spectacular array of naturally colored diamonds, including red color diamonds.
Diamonds occur in a restricted variety of colors — steel gray, white, blue, yellow, orange, red, green, pink to purple, brown, and black. Colored diamonds contain interstitial impurities or structural defects that cause the coloration, whilst pure diamonds are perfectly transparent and colorless. Diamonds are scientifically classed into two main types and several subtypes, according to the nature of impurities present and how these impurities affect light absorption:
Type I diamond has nitrogen (N) atoms as the main impurity, commonly at a concentration of 0.1 percent. If the N atoms are in pairs they do not affect the diamond’s color; these are Type IaA. If the N atoms are in large even-numbered aggregates they impart a yellow to brown tint (Type IaB). About 98 percent of gem diamonds are type Ia, and most of these are a mixture of IaA and IaB material: these diamonds belong to the Cape series, named after the diamond-rich region formerly known as Cape Province in South Africa, whose deposits are largely Type Ia. If the N atoms are dispersed throughout the crystal in isolated sites (not paired or grouped), they give the stone an intense yellow or occasionally brown tint (Type Ib); the rare canary diamonds belong to this type, which represents only 0.1 percent of known natural diamonds. Synthetic diamond containing nitrogen is Type Ib. Type I diamonds absorb in both the infrared and ultraviolet region, from 320 nm. They also have a characteristic fluorescence and visible absorption spectrum (see Optical properties of diamond).
Type II diamonds have very few if any nitrogen impurities. Type II diamonds absorb in a different region of the infrared, and transmit in the ultraviolet below 225 nm, unlike Type I diamonds. They also have differing fluorescence characteristics, but no discernible visible absorption spectrum. Type IIa diamond can be colored pink, red, or brown due to structural anomalies arising through plastic deformation during crystal growth—these diamonds are rare (1.8 percent of gem diamonds), but constitute a large percentage of Australian production. Type IIb diamonds, which account for 0.1 percent of gem diamonds, are usually a steely blue or grey due to scattered boron within the crystal matrix; these diamonds are also semiconductors, unlike other diamond types (see Electrical properties of diamond). However, an overabundance of hydrogen can also impart a blue color; these are not necessarily Type IIb.
Also not restricted to type are green diamonds, whose color is derived from exposure to varying quantities of radiation.
The majority of diamonds that are mined are in a range of pale yellow or brown color that is termed the normal color range. Diamonds that are of intense yellow or brown, or any other color are called fancy color diamonds. Diamonds that are of the very highest purity are totally colorless, and appear a bright white. The degree to which diamonds exhibit body color is one of the four value factors by which diamonds are assessed.
Color grading of diamonds was performed as a step of sorting rough diamonds for sale by the London Diamond Syndicate.
As the diamond trade developed, early diamond grades were introduced by various parties in the diamond trade. Without any co-operative development these early grading systems lacked standard nomenclature, and consistency. Some early grading scales were; I, II, III; A, AA, AAA; A, B, C. Numerous terms developed to describe diamonds of particular colors: golconda, river, jagers, cape, blue white, fine white, and gem blue, “brown”.
Grading the normal color range
Refers to a grading scale for diamonds in the normal color range used by internationally recognized laboratories (GIA & IGI for example). The scale ranges from D which is totally colorless to Z which is a pale yellow or brown color. Brown diamonds darker than K color are usually described using their letter grade, and a descriptive phrase, for example M Faint Brown. Diamonds with more depth of color than Z color fall into the fancy color diamond range.
Diamond color is graded by comparing a sample stone to a masterstone set of diamonds. Each masterstone is known to exhibit the very least amount of body color that a diamond in that color grade may exhibit. When sample stones are compared with the master stone, the grader assesses whether the sample has more, less or equal color to the masterstones. A grading laboratory will possess a complete set of masterstones representing every color grade. However, the independent grader working in a retail will possess a range of masterstones that covers only the typical grade range of color they expect to encounter while grading. A typical grading set of masterstones would consist of five diamonds in two grade increments, such as an E, G, I, K, and M. It is not common for a grader to possess a D masterstone, as the E masterstone is more useful in dividing the D and E color grades. The intermediate grades are assessed by the graders judgement.
Diamonds in the normal color range are graded loose, with the table facet facing downward and pavillion side upwards. When color grading is done in the mounting, other techniques will apply and the grade will usually be expressed as a range (for example F-G)
“D” color has a unique “icy” look to it. Diamonds that rate toward the colorless end of the range are sometimes known as “high-color” diamonds, and those toward the other end, “low-color” diamonds. These terms refer to the relative desirability (as demonstrated by market prices) of color grades, not the intensity of the color itself.
Yellow or brown color diamonds having color more intense than “Z”, as well as diamonds exhibitng color other than yellow or brown are considered fancy colored diamonds. These diamonds are graded using separate systems which indicate the characteristics of the color, and not just its presence. These color grading systems are similar to those used for other colored gemstones, such as ruby, sapphire, or emerald, than they are to the system used for white diamonds.
Colored diamond grading system
It refers to the color grading system used by internationally recognized laboratories (GIA and IGI for example)for colors that are not in the normal color range of diamonds. These laboratories uses a list of 27 color hues that span the full spectrum of colors. The tone and saturation of these hues are then described with one of nine descriptors;
- Faint,
- Very Light,
- Light,
- Fancy Light,
- Fancy,
- Fancy Intense,
- Fancy Vivid,
- Fancy Deep,
- Fancy Dark.
Color can also be determined using a device called the Gran Colorimeter, manufactured by Sarin Technologies. It measures from D to Z to Fancy Intense with an accuracy within ±½ of a color grade on loose stones from 0.25 to 10 carats (50 to 2,000 mg) (as low as 0.15 carat (30 mg) or as high as 20 carats (4 g) with reduced accuracy), and you can specify which grading scale it should use (GIA, GEM, IGI, AGS, HRD, and others). The accuracy is within ±1 color grade for mounted stones. If you diamond is a “G” color it will tell you whether it’s a “high G” or a “low G.”
The Gran colorimeter was first developed by Paul Gran in 1972 at Gran Computer Industries Ltd.
The Darya-I-Nur Diamond is one of the world's largest diamonds and definitely one of the unusual because of its pale pink color. It weighs about 182 carats (36.4 g) and its color is a pale pink which is one of the rarest to be found in diamonds. Its exact weight isn't known because its been mounted in its brooch setting for over 130 years. Its Persian name 'Darya-I-Nur' translates into English as the 'Sea of Light'
Diamonds that enter the Gemological Institute of America’s scale are valued according to their clarity and color. For example, a “D” or “E” rated diamond (both grades are considered colorless) is much more valuable than an “R” or “Y” rated diamond (light yellow or brown). This is due to two effects: high-color diamonds are rarer, limiting supply; and the bright white appearance of high-color diamonds is more desired by consumers, increasing demand. Poor color is usually not enough to eliminate the use of diamond as a gemstone: If other gemological characteristics of a stone are good, a low-color diamond can remain more valuable as a gem diamond than an industrial-use diamond, and can see use in diamond jewelry.
Diamonds that go out of scale in the rating are known as “fancy color” diamonds. Any light shade of diamond other than light yellow or light brown automatically falls out of the scale. For instance, a pale blue diamond won’t get a “G” or “K” color grade, it will get a Faint Blue or Light Blue grade. These 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. Fancy-colored diamonds such as the deep blue Hope Diamond are among the most valuable and sought-after diamonds in the world. The Aurora Diamond Collection of natural color diamonds is one of the most comprehensive diamond collections in the world.
- Haske, Martin. GIA GTL’s Color Grading Of Fluorescent Diamonds. (Retrieved March 15, 2005.)
John Turner (footballer). gia diamonds
John Turner (born February 12 1986 in Harrow, London) is an English footballer, who currently plays for King’s Lynn. He is 178cm (5′10″) tall and plays as a forward.
He joined Cambridge United’s youth scheme in the summer of 2002, after leaving Aston Villa’s youth academy..
He made his debut on 2003-04-12 in League Two against Exeter City, coming on with 15 minutes remaining, he scored the winner in the final minute of the match.
He scored his first (and so far only) hat-trick on November 20 2004 in League Two against Rushden & Diamonds. Cambridge United won the match 3-1. Whilst at Cambridge, he was loan out to Aldershot for a month.
As of the summer of 2005, he had played 82 matches for United, scoring 12 times.
Transferred to Rushden & Diamonds in January 2006 he was knocked out during his first appearance. He later played for Grays Athletic who loaned him out to Conference South sides Braintree and Bishop’s Stortford, before being released in May 2007.
Turner has since signed for King’s Lynn
Juul Haalmeyer. diamonds
Juul Haalmeyer is a costume designer, best known for doing costume design on several iterations of SCTV. In addition, he was the “leader” of the Juul Haalmeyer Dancers, a woefully inept troupe of variety show dancers made up mostly of writers and crew on SCTV. Haalmeyer also worked a costume designer for many television shows and specials like Bridge to Silence, All My Sons, Long Day’s Journey into Night, Noddy, the Shining Time Station Family Specials, Mr. Conductor’s Thomas Tales, Diamonds, The Last Diamond, Gullah Gullah Island, , Ace Lightning, Ghostwriter, Sesame Street and Big Bag.
The Acme of Control. diamonds
The Acme of Control is a card trick in which the magician shows two cards, inserts them into the deck, allows the spectator to shuffle the deck, takes the deck back, and is then able to produce the two cards in any way he pleases, such as from his pocket.
Assuming that the magician wishes to produce the cards from his pocket at the end, he starts with the five of diamonds and the four of hearts in his pocket before presenting the trick. He then removes the five of hearts and the four of diamonds that are in the deck, and shows them together to the audience. These cards are re-inserted into the deck, which is then shuffled by the spectator. At the end, the magician produces the similar pair of cards that have been in his pocket all along, apparently the same cards which were shuffled into the deck.
Thunderbolt (band). diamonds
Thunderbolt is a Norwegian heavy metal band that combines the classical influence of bands like Iron Maiden, Helloween, and Black Sabbath with a more modern, powerful sound like that of Bad Brains and Entombed.
After releasing their demo Bandits at 6 O’Clock in 2001, the band received multiple offers for a record contract and subsequently signed in Scandinavia with Face Front / WME (and Massacre Records outside of Scandinavia) for the release of their 2003 debut album Demons and Diamonds. The album received acclaim in Norwegian and international music press and was even appreciated by the mainstream Norwegian press — rare for a band in this genre.
Following the success of Demons and diamonds, the band played several gigs and festivals in Norway, Germany, and Scandinavia from 2003 through 2005.
Recording and mixing of the follow up album Love and Destruction was finished in the summer of 2005. However, due to matters in the hands of the record label it took quite a while to make administrative arrangements and bring this album to the public, It was finally released Friday 19. May 2006 and followed up by a Norwegian tour together with Paul Di’Anno (although prior to the release) as well as a major European tour supporting King Diamond (May-June 2006).
Aber Diamond. diamonds
Aber Diamond Corporation (; ) is a Toronto, Canada specialist diamond mining and retail company.
The company holds a 40% stake in the Diavik Diamonds Project. Production at the Diavik Diamond Mine, Canada’s second diamond mine, is operated by Aber’s joint venture partner, Diavik Diamond Mines Inc., a subsidiary of Rio Tinto Group. The mine began producing diamonds in November 2002.
Aber’s participation in the retail segment of the diamond pipeline is by means of its 51% controlling interest in Harry Winston, which they purchased in 2004. As of October 2006, Aber has a 100% ownership in Harry Winston.
Aside from its corporate office in Toronto, Aber Diamond also has a rough diamond sorting faciilty in Toronto and a marketing office in Antwerp, Belgium. Aber Diamond sells Tiffany & Co. about 25% of the diamonds in Aber’s share and sells the remainder on the Antwerp open diamond market through its rough diamond dealer subsidiary, Aber International.
Allnatt Diamond. gia diamonds
The Allnatt Diamond is a diamond measuring 101.29 carats (20.258 g) with a cushion cut, rated in color as Fancy Vivid Yellow by the Gemological Institute of America. This diamond is named after one of its holders, Major Alfred Ernest Allnatt, a soldier, sportsman, art patron and benefactor. While it is not known precisely where the Allnatt originated, many experts believe that it was probably found in what is now known as the De Beers Premier Diamond Mine.
The Allnatt’s origins are unknown prior to Major Allnatt’s purchasing of the diamond in the early 1950s. After purchasing the diamond, he commissioned Cartier to make a setting for it. The final setting was a platinum flower with five petals, a stem and two leaves, all set with diamonds. The Allnatt was resold at auction in May 1996 by Christie’s in Geneva for $3,043,496 US. At the time of its sale the Allnatt was 102.07 carats (20.414 g). and was graded Fancy Intense Yellow. After being sold to the SIBA Corporation, the diamond was re-cut to its current weight and the intensity was upgraded as a result.
The Allnatt was displayed as part of the Smithsonian’s “The Splendor of Diamonds” exhibit, alongside The De Beers Millennium Star and The Heart of Eternity.
List of diamond mines. diamonds
- “Diamond mine” redirects here. For the game from PopCap Games also known as Diamond Mine, see Bejeweled.
There are a limited number of commercially viable diamond mines currently operating in the world. Diamonds are also mined alluvially over disperse areas, where diamonds have been eroded out of the ground and deposited by water or weather action. There is also at least one example of a non-commercial diamond mine (Crater of Diamonds State Park).
- Botswana
- Damtshaa diamond mine
- Jwaneng diamond mine
- Letlhakane diamond mine
- Orapa diamond mine
- South Africa
- Other African locations
- Kampangala diamond mine, Congo
- Murowa diamond mine, Zimbabwe
- Williamson diamond mine, Tanzania
- Panna
- United States
- Crater of Diamonds State Park
Dresden Green Diamond. gia diamonds
The Dresden Green diamond is a 41 carat (8.2 g) natural green diamond that has a historical record dating to 1722, when a London news-sheet carried an article about it in its 25 October-27th edition.
It is named after the capital of Saxony, Germany where it has been on display for most of the last two centuries. It did make some sojourns following World War II, to the Soviet Union until 1958, and to the Smithsonian in Washington DC, USA in 2000, where it was displayed in the same room as the Hope diamond.
The stone’s unique green color is due to natural exposure to radioactive materials (see Diamond enhancement#Irradiation). The stone is being used to compare natural versus lab-produced green diamonds — it is hoped that it can be used to devise a test to differentiate between naturally green diamonds, which are quite rare, and lab-produced ones.
This diamond is located in the Staatliche Kunstsammlungen Dresden “The New Green Vault”
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Barry Hunter. diamonds
Barry Hunter (born 18 November 1968, Coleraine, Northern Ireland) is a former Northern Ireland international footballer,He made his name with Wrexham FC before tranfering to Reading for £400,000,On ending his playing career at Portadown FC, he had a short spell as the caretaker-assistant manager at Swindon Town under Adrian Williams.Williams and Hunter were replaced by Paul Sturrock and Kevin Summerfield. Joined Blackburn Rovers as a senior Scout in 2006. Responsible for team assessments and player recruitment. Co-hosts a football show on Reading107fm two nights a week. Recently achieved Certificate in Applied Management from Warwick University.
Winkle squeeze. gia diamonds
A winkle is a rare squeeze/endplay in contract bridge in which a trick is offered to the defenders but whichever wins the trick is then endplayed. Often one defender would be forced to offer a finesse or ruff and discard while the other could overtake and thereby promote a trick in that suit for declarer.
An example end-position, South needing 4 tricks:
On the play of the last spade, West and North let go clubs, and East is squeezed. Pitching a heart yields an immediate trick in that suit, but if a diamond is pitched declarer follows with Ace and 3 of diamonds. If East wins the trick, they must lead hearts conceding the last two tricks there. If West saves partner by playing the king of diamonds on the second diamond trick, they must then concede the last two tricks to dummy’s now high Ace of clubs and Jack of diamonds.
Eva Almos. diamonds
Eva Almos is a Canadian voice actress, who voiced Friend Bear and Swift Heart Rabbit in Nelvana’s Care Bears films and TV series, and also appeared in AlfTales.
Almos was also a writer of USA Network’s animated sitcom, Duckman, and as of 2006 has continued this job with An American in Canada and several animated series. In her heyday, she guest-starred in the Canadian television series, Diamonds.
In the 1980s Eva freelanced as a voice performer at the Toronto Radio Station, CKFM ( now CFMX), for in house radio commercials.
For a time in the mid 1980s she was romantically linked to Canadian Actor Jeff Wincott.
Jack of Diamonds (artists). diamonds
Jack of Diamonds (), also called Knave Of Diamonds, was a group of artists founded in 1909 in Moscow. The group included Robert Falk, Aristarkh Lentulov, Ilya Mashkov, Alexander V. Kuprin, and Pyotr Konchalovsky. The group’s members considered Paul Cézanne to be the only worthy painter to imitate, the others being too trivial and bourgeois for their tastes.
The name itself was coined by Mikhail Larionov for the exhibition of 1910. Among the famous painters that participated in the first Jack of Diamonds exhibition were Mikhail Larionov, Natalia Gontcharova, Kazimir Malevich (and later, Léopold Survage). Some artists eventually disagreed with the group’s ethos and formed the more radical Donkey’s Tail.
Brilliant (diamond cut). gia diamonds
Brilliant is the most popular cut shape for diamonds. The shape resembles that of a cone and is meant to maximize light return through the top of the diamond.
Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight; rarely is it less than 50%. The round brilliant cut is preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. Oddly shaped crystals such as macles are more likely to be cut in a fancy cut—that is, a cut other than the round brilliant—which the particular crystal shape lends itself to.
The brilliant cut was introduced in the middle of the 17th century. The first brilliants were known as Mazarins. They had seventeen facets on the crown (upper half) and are called double-cut brilliants.
Vincent Peruzzi, a Venetian polisher, increased the number of crown facets from 17 to 33 (triple-cut brilliants), thereby dramatically increasing the fire and brilliance of the cut gem — already much better in the double-cut brilliant than in the rose cut. When seen today, diamonds of that cut seem quite dull compared to modern-cut ones.
Around 1900, the development of diamond saws and good jewellery lathes enabled the development of modern diamond cuts, chief among them the round brilliant cut. In 1919, Marcel Tolkowsky analyzed this cut. His calculations took both brilliance (the amount of white light reflected) and fire (flashes of spectral colors) into consideration, creating a delicate balance between the two. His geometric calculations can be found in his book on Diamond Design.
In the 1970s, Bruce Harding developed another mathematical model for gem design. Since then, several groups have used computer models (e.g., MSU, OctoNus, GIA, and folds.net) and specialized scopes to optimize the round brilliant cut.
The modern round brilliant consists of 58 facets (or 57 if the culet is excluded); 33 on the crown (the top half above the middle or girdle of the stone) and 25 on the pavilion (the lower half below the girdle). In recent decades, most girdles are faceted. Many girdles have 32, 64, 80, or 96 facets; these facets are not counted in the total. While the facet count is standard, the actual proportions (crown height and angle, pavilion depth, etc.) are not universally agreed upon. One may speak of the American cut or the Scandinavian standard (Scan. D.N.), to give but two examples.
These days many people have over used Tolkowsky’s “ideal” model. The original model were general guidelines as there were several aspects of diamond cut that was not explored or accounted for in the original model.
Excerpts from GIA article What did Marcel Tolkowsky really say?:
Because every facet has the potential to change a light ray’s plane of travel, every facet must be considered in any complete calculation of light paths. Just as a two-dimensional slice of a diamond provides incomplete information about the three-dimensional nature of light behavior inside a diamond, this two-dimensional slice also provides incomplete information about light behavior outside the diamond. A diamond’s panorama is three-dimensional. Although diamonds are highly symmetrical, light can enter a diamond from many directions and many angles. This factor further highlights the need to reevaluate Tolkowsky’s results, and to recalculate the effects of a diamond’s proportions on its appearance aspects.
Another important point to consider is that Tolkowsky did not follow the path of a ray that was reflected more than twice in the diamond. However, we now know that a diamond’s appearance is composed of many light paths that reflect considerably more than two times within that diamond. Once again, we can see that Tolkowsky’s predictions are helpful in explaining optimal diamond performance, but they are incomplete by today’s technological standards.
Figures 1 and 2 show the facets of a round brilliant diamond.
Figure 1 assumes that the “thick part of the girdle” is the same thickness at all 16 “thick parts”. It does not consider the effects of indexed upper girdle facets.
Figure 2 is adapted from Figure 37 of Marcel Tolkowsky’s Diamond Design, which was originally published in 1919. Since 1919, the lower girdle facets have become longer. As a result, the pavilion main facets have become narrower.
The relationship between the crown angle and the pavilion angle has the greatest effect on the look of the diamond. A slightly steep pavilion angle can be complemented by a shallower crown angle, and vice versa. Graphs showing this trade-off are available from folds.net.
Other proportions also affect the look of the diamond:
- The table ratio is highly significant.
- The length of the lower girdle facets affects whether Hearts and arrows can be seen in the stone, under certain viewers.
- Most round brilliant diamonds have roughly the same girdle thickness at all 16 “thick parts”.
- So-called “cheated” girdles have thicker girdles where the main facets touch the girdle than where adjacent upper girdle facets touch the girdle. These stones weigh more (for a given diameter, average girdle thickness, crown angle, pavilion angle, and table ratio), and have worse optical performance (their upper girdle facets appear dark in some lighting conditions).
- So-called “painted” girdles have thinner girdles where the main facets touch the girdle than where adjacent upper girdle facets touch the girdle. These stones (such as EightStar-brand diamonds) have less light leakage at the edge of the stone (for a given crown angle, pavilion angle, and table ratio). Some diamonds with painted girdles receive lower grades in the GIA’s cut grading system, for reasons explained in the GIA article Painting and Digging Out.
Several groups have developed diamond cut grading standards. They all disagree somewhat on which proportions make the best cut. There are certain proportions that are considered best by two or more groups however.
- The AGA standards may be the strictest. David Atlas (who developed the AGA standards) has suggested that they are overly strict.
- The HCA changed several times between 2001 and 2004. As of 2004, an HCA score below two represented an excellent cut. The HCA distinguishes between brilliant, Tolkowsky, and fiery cuts.
- The AGS standards changed in 2005 to better match Tolkowsky’s model and Octonus’ ray tracing results. The 2005 AGS standards penalize stones with “cheated” girdles. They grade from 0 to 10.
- The GIA began grading cut on every grading report beginning January 1st, 2006 based on their comprehensive study of 20,000 proportions with 70,000 observations of 2,000 diamonds. The single descriptive words are as follows: Excellent, Very Good, Good, Fair, and Poor.
The distance from the viewer’s eye to the diamond is important.
The 2005 AGS cut standards are based on a distance of 25 centimeters (about 10 inches).
The 2004 HCA cut standards are based on a distance of 40 centimeters (about 16 inches).
Polish and symmetry are two important aspects of the cut. The polish grade describes the smoothness of the diamond’s facets, and the symmetry grade refers to alignment of the facets. With poor polish, the surface of a facet can be dulled, and may create blurred or dulled sparkle. It may constantly look like it needs to be cleaned. With poor symmetry, light can be misdirected as it enters and exits the diamond.
A diamond that has the top facet or “table facet” exactly perpendicular to the bottom of the diamond or “pavillion” and has its other facets precisely aligned with excellent symmetry, may show patterns that look like arrows from the top and hearts from the bottom. Generally it will need to be viewed loose under a gemscope to see the pattern very well. Although the hearts and arrows property is indicative of a top-tier cut, it does not always mean the diamond will be the most brilliant. Optimal facet placement is the key to brilliance and more important than facet patterning. Not all ideal round cuts will have the hearts and arrows effect either.
Diamond Trading Company. diamonds
The Diamond Trading Company (DTC) is a London-based subsidiary of the De Beers Group, specializing in the sale and marketing of rough (uncut) diamonds. The company forms an essential part of De Beers’ sales mechanism, maintaining an exclusive list of sightholders to which it sells all De Beers gem-grade diamonds coming to the market in a limited number of sales per year. Nicky Oppenheimer is chairman of DTC.
DTC receives uncut diamonds from all of De Beers’ mines around southern Africa, as well as some production from Alrosa in Russia. The diamonds are then sorted into over 16,000 categories, according to size, color, clarity, carat and quality (amount of inclusions). They are then combined into lots for sale to sightholders. Sightholders are invited to DTC’s London offices ten times per year and are given the opportunity to purchase lots of diamonds at prices set by DTC. According to a January 13, 2004 DTC media release ([1]), there are 84 sightholders, and three additional companies authorized to purchase diamonds from DTC for industrial use. In 2004, DTC’s sales were $5.7 billion, an increase of 3.2% over the previous year.
DTC also operates De Beers’ famous diamond marketing campaigns to consumers.
