The city of Golconda in south central India was the world’s only source of diamonds, apart from a small supply in Borneo, until 1725 when deposits were discovered in Brazil. It was around this time that the mines around Golconda became depleted.
Golconda diamonds have a Type IIa designation, meaning they are devoid of nitrogen. Type I diamonds, which contain nitrogen, have a slight yellowish tinge. “Only 2 percent of all diamonds are found in this Type II category,” said Thomas M. Moses, senior vice president of laboratory and research at the Gemological Institute of America (GIA). “Because they’re so pure, they transmit UV and visible light that Type I diamonds block. They have a clear, limpid, transparent nature.” Golconda has now become the maxim for the finest, rarest and purest of diamonds – a serious gem collector’s dream possession.
The largest Golconda diamond was discovered in the eighteenth century and weighed more than 410 carats. It was known as the Regent and was sold to the regent of France by the English prime minister. Although currently displayed in the Louvre, it is known to have decorated the chapeau of Marie Antionette as well as the hilt of Napoleon’s sword.
A rare blue diamond owned by the last Great Mughal Emperor of Persia, Aurangzeb, was known as the Darya-i-Nur (Sea of Light) and weighed 186 carats. It was stolen in 1739 in the ‘sack of Delhi’.