How to know the origin of the color in a diamond ?
More rare than whites, colored diamonds are a fantasy of nature. Only one in ten thousand is colored. Pink, brown, red, green ... their chromatic range is equivalent to that of the solar spectrum and due to an accident of growth at the time of crystallization. All colors exist but some are rare. Yellow and brown are the most common colors but these stones are considered gems only in the case of pure colors. The largest faceted diamond in the world is now a deep blue yellow stone, the Golden Jubilee, which weighs 545.67 carats.
Origin of the natural formation of color diamond
Without pressure, nor high temperature, no diamond. It is in the deep soils of the earth (layer called the mantle) that diamonds form. And if white diamonds are numerous, the formation of colored diamonds (also called diamonds fancy color) is much rarer ... The colors of the diamond come mainly from the gases found in the soil during its formation. On the planet earth, each geographical area shows a particular seismic and volcanic activity, as well as the presence of certain gases.
The kimberlite is a type of volcanic rock in which most diamonds are formed. It owes its name to the mining town of Kimberley in South Africa. But this is not the only diamond mining area. It is still almost impossible to determine the exact provenance of colored diamonds, which are in secretly protected areas. Mines that produce white diamonds are likely to come out of colored diamonds.
Argyle mine, the largest source of colored diamonds
Some mines stand out for the incredible colors they are the origin of: the Argyle mine in Australia gives the most beautiful diamonds pink, purple, purple and red. It was here that we found the largest purple diamond in history, 9.17 carats of crude and 2.83 carats when carved. Australia is the region that produces a wide range of diamonds in all shades of pink, as well as colors such as "champagne" and "cognac". The Argyle mine has managed to create a market for its champagne and cognac-colored diamonds and for these astonishing pink stones. Before this mine introduced brown and yellow diamonds into the gem market, they were used in the industry.
We also find the colors mentioned previously in Africa, Brazil and Russia on occasion. The Golconda mine in India was famous for the limpidity of its white diamonds, but also for giving the oldest blue diamonds in the history of mankind. This is the case of the diamond of more than 6 carats, the blue of Farnese having belonged to Queen Elizabeth of Spain and recently auctioned by Sotheby's Geneva. The mines of Zimi in Sierra Leone give the most pronounced yellows also called yellow-green diamonds or Canary diamonds.
The color diamond market
Considered as minors thirty years ago, these gems can today reach crazy sums, especially the yellow diamond because this color is, in China, that of the emperors. Colored diamonds are a specialized field, which has its own market and its own collectors. Many of these stones are so rare that they have become museum pieces. What the public does not know is that a pure color in a diamond is very rare! Until today there are more than 300 known colors and shades in the diamond. For example, a yellow diamond is often certified as "fancy yellow greenish" if it has green shades. Which makes it a stone of even greater rarity ...
Natural or artificial color diamond
These gems are sometimes a source of new difficulties for experts, forced to determine if their color is natural or not. The color of a diamond often results from impurities in the stone or natural radiation. Irradiation can also be used to change the color of a stone in the laboratory. That's why it is important to never buy a colored diamond without a certificate of quality and authenticity issued by one of the 3 largest gemological laboratories, namely the GIA, the HRD and the IGI. Gemologists note on the certificate if the diamond is natural, untreated and unmodified. It goes without saying that the difference in value and price between a natural colored diamond and an artificial colored diamond is huge!
There are several ways to turn the color of a diamond into a laboratory. The cyclotron gives it a kind of colored film, which can range from dark green to almost black in color. If you continue to heat the stone, the dark green becomes yellow, orange or brown. An electron accelerator produces a film of blue to blue-green color. By heating the stone more, the color can become yellow-orange, pink-purple or brown. Neutron treatment is the most commonly used form of irradiation today.