The 'Ocean Dream' has become the most expensive fancy vivid blue-green diamond ever sold at auction

British international auction house Christie's sold a rare blue-green diamond known as the 'Ocean Dream', which was found in Central Africa, for more than $17.3 million at its Magnificent Jewels sale in Geneva on Wednesday. 

The auction house said the 5.5-carat diamond is the largest fancy vivid blue-green diamond ever certified by the Gemological Institute of America. It exceeded its presale estimate of $8-12 million. It was cut from an 11.70-carat rough stone found in the 1990s. 

The gem was shaped into a triangular cut that preserved much of the original rough diamond. 

Christie's said the diamond attracted strong bidding before an unnamed private collector bought it. The bidding lasted around 20 minutes. The auction house said the final price set a new auction record for a diamond of its kind.

The Ocean Dream became widely known after it appeared at the Smithsonian Institution's 'Splendor of Diamonds' exhibition in 2003. 

"The Ocean Dream is a gemstone of rare distinction, returning to auction for only the second time in its history. Celebrated by the Smithsonian Institution as one of the eight rarest diamonds in the world, it stands as the largest fancy vivid blue-green diamond ever recorded," Max Fawcett, the global head of Christie's Jewelry, said in a statement released before the sale.

Details about the diamond's origin, including the mine and country where it was discovered, have never been publicly disclosed by gemological authorities or auction houses. Christie's and industry sources have only identified the stone as originating from Central Africa.

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The sale follows other high-profile auctions of rare diamonds mined in Africa. In May 2025, Sotheby's sold the 'Mediterranean Blue', a 10.03-carat blue diamond from South Africa's Cullinan mine, for around $21.5 million in Geneva.