Christie's has auctioned off the famed Archduke Joseph Diamond for US$21,474,525 ($26,312,654) including commission, a world auction record price per carat for a colourless diamond.
The price was well above the expected US$15 million and more than triple the price paid for it at auction almost two decades ago. The auction took place in Geneva.
The 76.02-carat diamond, with perfect colour and internally flawless clarity, came from the ancient Golconda mines in India.
It was named for Archduke Joseph August of Austria, the great grandson of both a Holy Roman emperor and a French king.
''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, told reporters.
''The market is not on the best form at the moment. The sale tonight was almost flabbergasting,'' Curiel said.
He added that the buyer wished to remain anonymous.
The seller was American jeweller Black, Starr & Frost.
''My understanding is that this stone is going to a museum and it will probably be the centrepiece,'' said Black, Starr & Frost's chairman Alfredo Molina.
The diamond was the star lot at Christie's semi-annual jewellery sale in Geneva.
Historical diamonds originating in the Golconda mines, virtually exhausted by the 18th century, include the Koh-i-Noor, now in the British crown jewels, and the blue Hope Diamond, part of the Smithsonian Institute in Washington, DC, Christie's 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 suberb quality to the legendary Koh-i-Noor,'' Rahul Kadakia, head of Christie's jewellery for the Americas and Switzerland, said.
In 1933, records show the Archduke deposited the stone in the vault of the Hungarian General Credit Bank.
''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,'' the auction house said.
Decades later it surfaced at auction in 1961 and again at Christie's in November 1993, netting 9.7 million Swiss francs, equivalent to US$6.5 million at the time, the auction house said.
The stone was subsequently ''slightly recut''.
- AP and Reuters