A 10.95 Ct Fancy Vivid Blue Diamond on Christie’s Block

The Bulgari Blue Diamond (above) is expected to fetch $12 million

The ring will be the highlight of Christie's Jewels: The New York Sale to be held on October 20. The rare color and size of the blue diamond will probably attract collectors and diamond traders such as Lawrence Graff to this auction.

In recent years, prices for top-quality colored diamonds have increased rapidly, driven by collector demand and increasingly limited supply. Large natural blue diamonds - in particular those possessing the coveted Vivid Blue tone and saturation - are amongst the most sought after colored diamonds, earning exceptional prices of well over $1 million per carat at auction.

In December 2008, Christie’s auctioned the Wittelsbach-Graff Diamond, a 35.56 carats fancy deep grayish blue diamond, for $24.3 million, a record price for an auctioned diamond.

The ring is being offered by a private European collector who has kept the ring in his family for almost 40 years. According to family tradition, the ring was given as a gift from the collector to his wife in celebration of the birth of their first baby boy. The sale price in 1972, when the ring was commissioned from Bulgari in Rome, was about $1 million, a fortune at the time.

Christie’s has arranged a global preview tour of the Bulgari Blue Diamond and other highlights of the October auction. The items will be viewable at Christie’s Geneva, Hong Kong and London throughout this month and at Christie’s New York in mid-October, during the week leading to the auction.