On April 27, Sotheby’s Hong Kong will hold a single-lot auction for the largest and potentially most valuable blue diamond ever to come under the hammer—a 15.1 ct. internally flawless step-cut, called the De Beers Cullinan Blue.
The diamond has a value “in excess of $45 million,” said Sotheby’s. (There’s a reserve, but it’s not public.) The gem has been graded fancy vivid blue and internally flawless by the Gemological Institute of America.
There have been only five blue diamonds over 10 carats ever to appear at auction, and, until now, none of them has topped 15 carats.
“It is one of the most important diamonds we have ever sold at auction,” Wenhao Yu, chairman of jewelry and watches at Sotheby’s Asia, tells JCK. “It is not easy to do a step-cut colored diamond. It is type IIB. It is a one-of-a-kind masterpiece, comparable to an important artwork. It’s a unique piece of nature.”
He doesn’t know if the diamond will fetch a record price, though in the past, aqua diamonds like the Blue Moon have.
“That’s one of the things about auctions, you never know until that night,” he says. “It has the potential to set a record. Not many diamonds can compare to this one.”
An important colored diamond hasn’t come on the market in a while, he says, but he notes the top auction pieces have done extremely well.
“The price for rough has risen by 10%–15% since last year. The market for top artwork, top masterpieces, has been really strong.”
Unlike other recent auctions, the auction house hasn’t announced whether it will accept cryptocurrency.
“We wouldn’t shut the door completely [to crypto],” says Yu. “If there is a serious qualified buyer, we’ll consider it.”
The diamond was named after the mine where it was discovered, the Cullinan, in Gauteng province, South Africa. Yu believes its provenance could add to its value—similar to the way a Kashmir sapphire or a Colombian emerald carries extra cachet—as the Cullinan is considered the world’s only source of important blue diamonds.
Photo © De Beers Jewellers.