The De Beers Cullinan Blue

On April 27, The De Beers Cullinan Blue diamond was auctioned by Sotheby’s Hong Kong for a price of $57.5M, making it the third most expensive jewel ever sold at auction. The final day was a bit like tennis great Serena Williams’ quest for wins #24 to tie Margaret Court’s recod of Grand Slam Singles tournaments — and then nail the record for herself at #25 wins.

This extraordinary 15.10 carat step-cut blue diamond had a preauction estimate of $48 million, and clocking $57.5M in the Sotheby’s Hong Kong auction sale was impressive. Did it add another chapter of precious storytelling to The De Beers Cullinan Blue? No.

To be precise the exact sale price of $57,471,960 was so very close to that of the ‘Oppenheimer Blue’, which sold for $57,541,779 in 2016. Losing to ‘The Pink Star’ sold for $71.2 million in 2017, also at Sotheby’s Hong Kong is an easier pill to swallow.

Four bidders were involved in the eight-minutes of auction bidding, with an anonymous phone bidder taking ownership of the precious De Beers Blue.

“With its powerful vivid color, and breathtakingly beautiful cut, it is truly a once-in-a-generation stone, and quite simply the greatest blue diamond of its size I have ever seen during my 31-year-career at Sotheby’s. [The auction] result is a clear confirmation of the growing appreciation, and awareness of the great scarcity of blue diamonds around the world,” said Sotheby’s Asia Chairman Patti Wong.

The Cullinan Blue Discovery

In April 2021 an exceptional rough stone weighing 39.34 carats was discovered at South Africa’s Petra Diamonds Cullinan mine. This phenomenal blue diamond was sold in July 2021 for $40.1 million to the De Beers and Diacore partnership, achieving a price of $1,021,357 per carat.

Cullinan is known as the world’s most important source of blue diamonds, as well as being the birthplace of the 3,106-carat Cullinan diamond, which was cut to form the 530-carat Great Star of Africa.

The operation also yielded the 317-carat Second Star of Africa. They are the two largest diamonds in the British Crown Jewels. De Beers divested itself of the mine in 2007, part of a larger business strategy to turn to the marketing and selling of diamonds, while turning over mining to more local ownership.

It’s noteworthy that $40 million of the $48 million estimate did go to the Petra mining operation. There is significant loss in ‘waste’ created in cutting the De Beers Cullinan Blue. Presumably there is some value in the ‘waste’ but common sense suggests that the perfect blue diamond will sell at a price higher than $48 million, the highest estimate ever for a blue diamond.

The De Beers Cullinan Blue has made only two stops on the way to its April 27 Sotheby’s auction. The blue diamond was cut at Diacore, a De Beers partner whose maser cutters cut and polished the gem. This process is extraordinarily challenging with zero tolerance for the slightest mistake. The Cullinan Blue then arrived at the Gemological Institute of America, where it was found to be the largest internally flawless step-cut vivid blue diamond its lab had ever graded.

Natural blue diamonds are extremely rare, comprising only about 0.02% of all mined diamonds. Presently, these gems are found in only three mines globally: the Cullinan mine in South Africa, the Golconda mine in India, and the Argyle mine in Australia.