Diamond Color
The Gemological Institute of America uses as "D" to "Z" scale for
color where "D" is colorless and "Z" is yellow:
- colorless: D, E, F
- near colorless: G, H, I, J
- faint yellow or brown: K, L, M
- very light yellow or brown: N, O, P, Q, R
- light yellow or brown: S, T, U, V, W, X, Y, Z
Colorless diamonds are priced higher than yellow diamonds. However, when a diamond's color is more intense than the "Z" grading, it enters the realm of "Fancy Color". In this case, the intensity of the color in the diamond plays a major role in its value. The value of a Fancy Color Diamond may far surpass that of colorless diamonds, if the intensity of the color is high and the color is rare. A diamond may come in all colors of the rainbow.
A fancy brown diamond may have low value, relative to colorless diamond. However, a fancy pink or blue diamond will command higher prices. Fancy-colored diamonds such as the deep blue Hope Diamond are particularly valuable.
Brown rather than yellow as the color became more common as Australian diamonds entered the market and is generally less appreciated by consumers and sold at a greater discount if the color is readily visible.
80% of the diamonds produced are poorer quality (discolored, less transparent) diamonds which are used as industrial diamonds, where their extreme hardness is useful in cutting and grinding otherwise intractable materials (including other diamonds). Lately, gas-phase deposition processes have been devised that allow thin diamond films to be grown on some surfaces, greatly increasing the durability of some machine tools.
While the prices are higher for colorless diamonds, the exact color most valued by a consumer is a matter of personal preference, with some preferring the very transparent D-F range, while others prefer the "warmer" colors in the G-J range and still others prefer a clearly visible tint.
Sources
Historically diamonds were found in alluvial deposits in southern India which are now worked out. Most diamond deposits are in Africa, notably in South Africa, Namibia, Botswana, the Republic of the Congo and Sierra Leone. Revolutionary groups in some of those countries have taken control of diamond mines, using the conflict diamonds to finance their operations.
There are also commercial deposits in the Northwest Territories of Canada, the Russian Arctic, Brazil and in Northern and Western Australia. Occasionally diamonds have been found in glacial deposits in Wisconsin and Indiana. The Wisconsin finds can be explained by recent Canadian discoveries, but the diamonds found in Indiana must have come from an as yet undiscovered source in Quebec as the movement of ice was from northeast to southwest. Tiny nanometer sized diamonds, often called nanodiamonds, are also found as presolar grains in primitive meteorites.
Diamonds have been manufactured artificially for over fifty years, and very recently companies began marketing them to the public as jewelry and in technology. For more information see Artificial diamond.
A city of major importance in diamond trade is Antwerp, Belgium. It is estimated that nearly 90% of the world's rough diamonds, 50% of cut diamonds, and 40% of industrial diamonds trade hands in Antwerp. The industry is represented by the Diamond High Council (HRD). Before Antwerp the port city of Bruges saw most diamond trade, holding its position since the 13th century. Toward the 15th century Bruges declined, its port choked with silt.
Antwerp had been the world centre of diamond trade since the 16th century, until the city's 1585 capture by the Spanish. Amsterdam then supplanted Antwerp as a trading centre, until the latter's resurgence beginning in the 19th century.