Christie’s reoffers largest known fancy vivid blue-green diamond at Geneva auction

More than a decade after it last crossed Christie’s Geneva block, the 5.50-carat Ocean Dream is returning with a CHF 7 million to CHF 10 million estimate that underscores why the most compelling diamonds are prized for color as much as size. Christie’s says the triangular-cut stone is the largest fancy vivid blue-green diamond known to exist, a distinction that gives the sale significance well beyond the headline figure.

The diamond first sold at Christie’s Geneva on May 14, 2014, for CHF 7,781,000, or about $8.63 million at the time. GIA said that result worked out to roughly $1.4 million per carat, then a record price for a diamond of that color. Twelve years later, the same stone is back on the market, and the new estimate places it in the rarefied territory where collectibility depends on more than the thrill of a big number.

What makes Ocean Dream so arresting is not only its scale, but its hue. GIA describes fancy-color diamonds as among the most highly valued gemstones, and large vivid stones are exceptionally scarce. Blue-green sits in that narrow band of color that feels both mineral and atmospheric, like seawater caught in crystal. That emotional charge is part of its appeal, but so is the discipline of the market: collectors pay for stones that combine intensity, size, and a clean, recognizable pedigree.

Christie’s says the diamond was extracted from a 11.70-carat rough found in Central Africa in the 1990s. It was then polished into a modified triangular brilliant in New York by Cora Diamond Corp., and it earned the Ocean Dream name for its saturated blue-green color. The gem is mounted in a ring of sculpted rock crystal, pavé-set diamonds and pink diamonds, set in platinum and gold, a frame that heightens the stone’s color rather than competing with it.

Its history helps explain its staying power. GIA says the diamond has been certified by the organization since its founding in 1931, and historical material places Ocean Dream among seven of the world’s rare gem diamonds displayed at the Smithsonian Institution in Washington, DC, in 2003. That museum-level provenance matters because truly collectible colored diamonds are not judged only by auction theatrics. They are measured by rarity, recognizability, condition, and the depth of their record in the market.

As Geneva prepares for the sale in May 2026, Ocean Dream stands as a reminder that the best colored diamonds do more than sparkle. They carry a geological accident, a documented history, and a visual identity strong enough to survive a dozen years away from the spotlight.