A record blue diamond co-owned by De Beers far outstripped its presale estimate in a stand-alone sale at Sotheby’s in Hong Kong, garnering HKD 450.9 million ($57.5 million), the auction house said Wednesday.
The step-cut, 15.10-carat, fancy-vivid-blue, internally flawless stone, called the De Beers Cullinan Blue, is the largest of its color to appear at auction. The stone, which sold to an unnamed buyer, had been expected to fetch up to $48 million.
Petra Diamonds discovered the 39.35-carat rough in April 2021 at its Cullinan mine in South Africa. In July, De Beers and Diacore bought the stone for $40.2 million, and Diacore manufactured the piece into the final polished.
To date, only five blue diamonds weighing more than 10 carats have come to auction, none of which has exceeded 15 carats, Sotheby’s explained. Similar blue diamonds have also fetched high prices, including the Blue Moon of Josephine, a cushion-shaped, 12.03-carat, fancy-vivid-blue, internally flawless diamond that sold for $48.5 million at Sotheby’s Geneva in 2015. Meanwhile, the Oppenheimer Blue, a step-cut, 14.62-carat, fancy-vivid-blue, VVS1-clarity stone, garnered $57.5 million at a Christie’s Geneva sale in 2016.