Largest blue-green diamond could fetch US$12M at auction

A 5.50-carat, triangular cut fancy vivid blue-green diamond – the largest of its kind ever recorded – is expected to sell for as much as US$12.74 million when it goes under the hammer at Christie's Geneva in May.

Christie’s revealed that “The Ocean Dream” is the largest fancy vivid blue-green diamond known to exist as certified by the Gemological Institute of America (GIA) since the organisation’s founding in 1931.

The diamond is fashioned in a striking triangular shape and was extracted from a rough found in Central Africa in the 1990s that weighed 11.70 carat. According to the auction house, a stone of this colour and size is extremely scarce. Adding to its rarity, the diamond is Type Ia, making it among the purest of natural gems.  

Max Fawcett, global head of Christie’s Jewellery, said the Smithsonian Institution regards the diamond as one of the eight rarest diamonds in the world.

“An exceptional jewel of profound rarity and allure, The Ocean Dream is a highlight not to be missed, with previews taking place in Bangkok and Hong Kong, ahead of the auction in Geneva this May,” added Fawcett.

The Ocean Dream will be offered on May 13, 2026 at the Magnificent Jewels auction in Geneva where it is estimated to achieve CHF7 million to CHF10 million (approximately US$8.92 million to US$12.74 million).

It is returning to auction for the second time since it was previously sold at Christie's Geneva in May 2014 for CHF7.7 million (around US$9.8 million, at current exchange rates).

The Ocean Dream made its debut at Splendor of Diamonds in 2003, a landmark exhibition organised by the Smithsonian Institute’s Museum of Natural History in Washington, DC. Seven of the world's most extraordinary diamonds, representing a rainbow of red, orange, yellow, pink, blue, blue-green, and white hues, were also exhibited together for the first time at The Harry Winston Gallery.

The Ocean Dream was then described as one of the rarest known diamonds, with no record of any other diamond of that colour and size. All eight diamonds, which were all discovered after 1980, included: The 203.04-carat De Beers Millennium Star; an unnamed diamond weighing 103 carats; the 101.29-carat Allnatt; the 59.60-carat Steinmetz Pink; the 27.64-carat Heart of Eternity; the 5.54-carat Pumpkin Diamond; the 5.50-carat Ocean Dream; and the 5.11-carat Moussaieff Red.

News by @JNA