The 35-carat "Beau Sancy" diamond was worn by Marie de Medici, Queen consort of Henry IV, at her coronation in 1610.
Five bidders spanning three continents competed for the historic jewel at a Sotheby's auction where there was little evidence of the current global financial woes.
An anonymous telephone bidder purchased the jewel, put on the market by the House of Prussia and described by Sotheby's as one of the "most fascinating and romantic" gems ever to come to auction.
The buyer paid 9,042,500 francs ($9,699,618) including the buyer's premium for the pear-shaped, double rose cut diamond -- more than double the $2 million to $4 million estimate.
"You are buying an historic work of art -- you are not buying a diamond," said Philipp Herzog von Württemberg, chairman of Sotheby's Europe, following the sale.
"I fell in love with it when I saw it. It's the cut, it's the history," he said.
The Beau Sancy attracted bids from North America, Europe and Asia, he said, refusing to give further details about the buyer.
The diamond's royal connections date back to 1604 when it was bought for Henri IV of France at the insistence of his wife Marie de Medici who wore it atop her crown at her coronation.
Later that century it was acquired by the Dutch and used to seal the wedding of Willem II of Orange Nassau to Mary Stuart, daughter of Charles I of England.
Stuart pawned the rose-cut gem to finance her brother Charles II's fight for the throne.
In 1702, the first king of Prussia gave it pride of place in the new royal crown and it has passed through generations of the House of Prussia until today.
"We've sold much larger diamonds but it has this wonderful romantic history, an unparalleled royal history -- it has never been in non-royal hands," said David Bennett, co-chairman of Sotheby's Switzerland, ahead of the sale.
The Beau Sancy went under the hammer at Geneva's Beau Rivage hotel as part of Sotheby's "Magnificent Jewels and Noble Jewels" sale.
A second historic diamond, a 7.3-carat "fancy yellow" formerly belonging to Charles Edward Stuart, one-time pretender to the thrones of Great Britain and Ireland, sold to a telephone bidder for 902,500 francs ($968,085) including the buyer's premium.
More commonly known as "Bonnie Prince Charlie", his attempts to make the Stuarts regain the crown failed and following the Battle of Culloden in 1745 he went into exile in France and Italy, where he is thought to have offered the gem to the Corsini family in gratitude for their support.
A pearl and diamond tiara created in 1920 by French jeweller Chaumet for the marriage of Prince Alexandre Murat to Yvonne Gillois meanwhile sold to a caller for 3.6 million francs ($3.8 million), well over its 1.4 million franc estimate.
The headpiece boasts one of the largest natural pearls ever recorded, according to Sotheby's.
On Monday a collection of 70 jewels belonging to billionaire philanthropist Lily Safra was sold by auctioneer Christie's in Geneva, raising $37.9 million for charity.
Brazil-born Safra, 77, was married to the Jewish-Lebanese banker Edmond Safra who died in a blaze at his Monte-Carlo penthouse in 1999.
The Elton John AIDS foundation, a water treatment programme in Brazil and children's hospital in Israel are among 32 charitable institutes to benefit from the sale of the gems, many of them created specially for Safra by renowned Paris jeweller JAR.