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.
The seller was California-based jeweller Black, Starr & Frost.
"My understanding is that this stone is going to a museum and it will probably be the centrepiece," Black, Starr & Frost's chairman, Alfredo Molina said.
Diamonds and gemstones were a refuge for investors in difficult economic times, he said.
"There is a crisis and people don't trust governments and banks. Paper money is a depreciating asset," he added.
The diamond was the star lot at Christie's semi-annual jewellery sale in Geneva, which fetched 76.6 million Swiss francs, with 290 of 348 lots sold.
Nineteen lots went for more than US$1 million each, the auction house said. They included a brooch with a Sri Lanka sapphire weighing 60.44 carats, surrounded by diamonds, that sold for 1.7 million francs.
Historical diamonds originating in the Golconda mines include the Koh-i-Noor, now part of the British crown jewels, and the blue Hope diamond, owned by the Smithsonian Institute in Washington, United States.
"The Archduke Joseph diamond is the finest and largest perfect Golconda diamond ever to appear at auction. It is comparable in its noble lineage and superb quality to the legendary Koh-i-Noor," Rahul Kadakia, head of Christie's jewellery for the Americas and Switzerland said.