On Nov. 11 in Geneva, Sotheby’s will auction the Blue Moon, a 12.03 ct. internally flawless vivid blue estimated to sell for between $35 million and $55 million.
If it achieves the top price in that range, it will set a record for the most valuable diamond ever sold at auction. The current title is held by the Graff Pink, a 24.78 ct. fancy intense pink that sold for $46.1 million in November 2010.
The cushion brilliant-cut Blue Moon is among the few blues with a fancy vivid grade — the highest rating for a colored diamond—ever to go under the hammer.
The stone comes from a 29.62 ct. piece of rough discovered by Petra Diamonds at the Cullinan mine in South Africa in January 2014. It sold for $25.6 million a month later to New York City – based Cora International, which then spent six months cutting and polishing it.