Diamonds with black as the primary dominant colour are unique. Blacks owe their colour to minute inclusions and random clustering throughout the stone rather than trace elements like nitrogen, boron and hydrogen that produce colour in most diamonds. The back diamonds have a unique brilliance as it seems to emanate from sheer darkness with the absorption of light by a pure black diamond being almost complete. These stones tend to go in and out of fashion and, unlike most of the other fancy coloured diamonds which are transparent, these stones are usually opaque, yet they still display the wonderful ‘adamantine’ luster almost unique to diamond.
Black diamonds were originally named “carbonados” by Brazilian garimpeiros (small-scale independent miners) who discovered them in quantity in 1840. Common names for black diamonds include jet black, gun metal black, etc. The rare pure specimens can command huge prices but the more common class of black diamonds have streaks that are colourless or gray which lead to pitted surfaces. These diamonds are comparatively reasonably priced (in the high four to low five figures per carat).
The black diamond rough is mined in Borneo and the Western Transvaal region of South Africa. The secondary hues and colour modifiers for black diamonds are gray, white, etc. Natural black diamonds are difficult to cut and polish due to their hardness. This is one of the major reasons for enhancing the diamonds to black by either heating or irradiation. Most black diamonds on the market, especially those with low prices, are enhanced