The De Beers Blue Cullinan diamond is up for auction and is set to break a number of records in the process.

Auctioneer Sotheby’s will facilitate the sale of the rare blue stone. The company has set a late-April date as the fast-approaching day on which bidding will take place.

The auction house also announced that the 15.10-carat step-cut diamond is the largest ever vivid blue diamond to go up for auction.


It was cut by De Beers from a rough stone discovered in April 2021, and is also the largest internally flawless step-cut vivid blue diamond that the Gemological Institute of America (GIA) has ever graded.

The rarity of this kind of stone cannot be understated, with only five blue stones of this quality over 10 carats ever going to auction.

Bruce Cleaver, De Beers CEO, commented: “This diamond ranks as one of the best De Beers has ever seen.

“It is extremely rare and unique, and as the Home of Diamonds, De Beers is pleased to join together with Sotheby’s to bring this diamond to the world.”

Meanwhile, the GIA’s report on the diamond read: “Achieving a fancy vivid colour grade in a step-cut or emerald-cut adds to the rarity, since most other fancy shapes intensify the body colour more efficiently in the face-up position than step-cuts.

“To achieve a fancy vivid grade with a step-cut or emerald-cut, the inherent body-colour has to be stronger than virtually every other fancy shape.”

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