18.1 million Swiss francs is today's daily digit in Europe.
"Sold to you madame for 18.1 million francs thank you very much"
The $21.5 million sale took place at Christies in Geneva.
(SOUNDBITE)(English) FRANCOIS CURIEL, PRESIDENT OF CHRISTIE'S ASIA, SAYING:
"It's a world record price for a Golconda D colour flawless diamond and it's a world record price also per carat for a diamond of this importance."
The Indian diamond is called 'Archduke Joseph' after its original owner - a Hungarian prince from the Habsburgs line.
It weighs 76 carats and is the size of a large strawberry.
It was bought from international jewellers Black by an anonymous bidder - Alfredo Molina is its chairman.
(SOUNDBITE)(English) VENDOR OF THE ARCHDUKE JOSEPH DIAMOND, ALFREDO J. MOLINA FROM THE JEWELLERY COMPANY BLACK, STARR AND FROST, SAYING:
"I congratulate the buyer, because they've truly acquired something that is of tremendous history and one of the most beautiful, if not the most beautiful diamond in the world"
Diamond prices generally have fallen 2 percent in recent weeks - but this $21.5million gem clearly has an added sparkle.
Daily digit: World record diamond (1:06)
Nov. 14 - Archduke Joseph diamond fetches world record $21.5 million at auction. Hayley Platt reports. ( Transcript )