The Beau Sancy diamond, one of the world’s most famous diamonds, has sold for $9.7 million at a Sotheby's auction in Geneva, about five times the pre-sale estimate.

The 34.98-carat diamond has been described as "one of the most important historic diamonds ever to come to auction" and has circulated throughout Europe’s royal families for over 400 years. The diamond originated from the Golconda mines in India and was named after Nicolas de Harlay, Lord of Sancy, in Constantinople, who acquired it in the 1500s. French king Henry IV bought it for his wife Marie de Medici in 1604, and she wore it at her coronation as Queen consort in 1610.

"The legendary Beau Sancy is a truly magical stone that has entranced generations of royal owners and continues to exert a powerful influence over all who see it," said David Bennett, Sotheby’s chairman of jewelry in Europe and the Middle East.

About five bidders competed for the diamond. An anonymous bidder won the auction.

"After a battle of nearly eight minutes, the celebrated jewel was finally bought by an anonymous buyer bidding over the telephone," said Sotheby's.

"Stones from royal collections hardly ever appear at auction. In my career this is an absolute one-off," said Bennett, who also mentioned that estimating the value of the stone was difficult, given its size and rarity.

The Golconda mines in India were the world’s sole source of diamonds until mines were discovered in Brazil in the 1700s. Other famous Golconda diamonds include the Hope diamond, the Koh-i-Noor, and Darya-e-Nur.