The rare and internally flawless diamond was sold for more than double the amount a bidder had paid 19 years ago. "It is a world record for a Golconda diamond and a world record price per carat for a colourless diamond," said Francois Curiel, director of Christie's international jewellery department.
"The market is not on the best form at the moment. The sale tonight was almost flabbergasting," he told newspersons at the saleroom.
Archduke Joseph August of Austria, who died in 1962, owned the Golconda diamond and hence it is known as the Archduke Joseph Diamond. In 1933, the Austrian prince deposited the diamond in the Hungarian General Credit Bank's vault.
"Three years later it was sold to a European banker, and kept in France, locked away in a safe deposit box, where fortunately it remained undiscovered during World War Two," Christie's said.
The Archduke Joseph Diamond was seen at an auction in 1961 and again in Nov 1993 when Christie's conducted another auction for it. Back then, the successful bidder paid 9.7 million Swiss francs (6.5 million US dollars) for the diamond whose size is almost the same as that of a large strawberry.
Yesterday, the first bid was for 8 million Swiss francs but others swiftly came up with higher bids. The person who ultimately made the record bid of 20.355 million Swiss francs by telephone does not wish to reveal his or her name, the auction house said.
"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," said Rahul Kadakia, head of Christie's jewellery for the Americas and Switzerland.
Black, Starr & Frost put up the Archduke Joseph Diamond for auction. Reuters quoted the California-based jeweller's chairman Alfredo Molina as saying, "My understanding is that this stone is going to a museum and it will probably be the centrepiece."