The world's largest blue diamond, a 15.10- carat diamond called "The De Beers Cullinan Blue," sold for over $57 million at auction. The diamond was expected to sell for $48 million. There was an eight minute bidding war between 4 potential buyers, but an anonymous buyer won via phone.
A press release from Sotheby's says the diamond comes from South Africa's Cullinan mine and was discovered in April 2021. Quote:
"In its masterfully crafted, newly formed state, it now re-emerges as the largest vivid blue diamond ever to appear at auction and the largest internally flawless step cut vivid blue diamond that the Gemological Institute of America (GIA) has ever graded. Blue diamonds of this importance are exceptionally rare, with only five examples over 10 carats ever having come to auction, none of which have exceeded 15 carats, making the appearance of this flawless gem a landmark event in itself."
The final price was $57,471,960. The second most expensive blue diamond to sell at auction. The most expensive blue diamond to sell at auction was the 14.62-carat "Oppenheimer Blue" which sold in 2016 for $57,541,779. That difference is just under $70,000.