A huge, internally flawless diamond from India's fabled Golconda mines was sold at auction in Geneva for a record 20.355 million Swiss francs (HK$157.8 million), Christie's said.
The rare, colourless stone weighing 76.02 carats, and roughly the size of a large strawberry, once belonged to Archduke Joseph August of Austria, a prince of the Hungarian line of the Habsburgs, who lived from 1872 to 1962.
On Tuesday it fetched more than double the price paid for it at auction almost two decades ago.
"It is a world record for a Golconda diamond and a world record price per carat for a colourless diamond," Francois Curiel, director of the international jewellery department at Christie's, said.
The gem's pre-sale estimate was 15 to 25 million Swiss Francs.
The previous record was held by the "Beau Sancy", a pear-shaped diamond of 34.98 carats, sold by rival Sotheby's for 9 million Swiss francs last May.
Curiel added that the buyer, who bid by telephone, wished to remain anonymous.