Fancy Colour Diamond History and Lore

Fancy-coloured diamond, history, 5.03-carat, DeYoung, red
The 5.03 carat DeYoung Red is an exceptionally rare coloured diamond. Chip Clark, - Courtesy Smithsonian Institution, National Museum of Natural History.
The world’s first diamond colour-grading system dates back to sixth-century India. The system was based on the country’s ancient class structure. Members of different status levels, or castes, were only permitted to own and wear diamonds of a specific colour. Thus, diamonds served as a badge of rank.
The priests and rulers, the Brahmins, were allowed to own diamonds that were “whitest of the conch, of the lotus, or of the rock crystal” (white to colourless). The landowners and warriors were assigned diamonds that were “the brown colour of the eye of the hare”. The merchant class was only allowed to own diamonds that were the “pretty nuance of a petal of a kadl [flower]” (yellow). And members of the lower classes were assigned diamonds with “the sheen of a burnished sword” (grey or black). Kings, however, were free to possess diamonds of any colour. 
Diamond colour-grading systems have evolved a lot since that time. Today, there are well-established methods for judging diamond colour based on much more than a comparison to conch shells, rabbits’ eyes and flower petals. And the only restrictions to owning different colours are based on availability and affordability.
While fancy colour diamonds have traditionally been a small part of the diamond business, their popularity and availability have grown in the past few decades. In the 1980s the Argyle mine in Australia began marketing its brown stones under trade names like “Champagne” and “Cognac”. Argyle reached its goal of making the public more aware of fancy colour diamonds and dropped its marketing campaign in the late 1990s. Today, the Argyle mine still produces brown diamonds, but it’s more famous as the world’s major source of rare pink diamonds.

Rare pink and violet diamonds
These rare pink and violet diamonds make up a tiny but important fraction of the Argyle mine’s production. - Courtesy of Rio Tinto Diamonds
The most well-known historical and current sources of fancy colour diamonds are India, South Africa and Australia. Other diamond mine locations, including Brazil, Venezuela, Guyana and Indonesia, also produce fancy colour diamonds.

Brown Diamonds
Brownish diamonds, like these crystals and round brilliants, constitute the bulk of
Argyle’s production.