A gemstone once described as a "unicorn" in gemological circles is about to re-emerge on the global stage. The legendary "Ocean Dream" — the largest Fancy Vivid blue-green diamond ever recorded — will headline the Magnificent Jewels sale at Christie's Geneva on May 13, where it is expected to achieve up to CHF 10 million (approximately $12.8 million).
Weighing 5.50 carats, this extraordinary gem is fashioned in a striking modified triangular brilliant cut, a shape chosen not just for beauty, but for survival. The triangular shape was similar to the original 11.70-carat rough diamond and required the least amount of cutting. Blue-green diamonds are among the rarest color combinations in the world, and preserving their delicate hue during cutting is a high-stakes challenge. In fact, experts have described the process as a “gamble,” because excessive heat from the cutting process — even above 300°C (572°F) — can permanently alter the stone’s color, turning it brown or black. The Ocean Dream’s final form is a triumph of patience and precision, retaining its mesmerizing, saturated tone.
That distinctive color comes from an equally rare natural phenomenon. While blue diamonds owe their hue to trace amounts of boron, green and blue-green diamonds like The Ocean Dream gain their color from exposure to natural radiation deep within the Earth over millions of years. For such a diamond to develop a vivid, stable color, it must remain in just the right conditions — close enough to radioactive elements, yet cool enough to avoid color degradation. The result is a gem so rare that few comparable examples exist.
The Ocean Dream’s mystique was cemented in 2003, when it was showcased at the Smithsonian National Museum of Natural History as part of the landmark “Splendor of Diamonds” exhibition in the Harry Winston Gallery. There, it stood alongside some of the most famous diamonds ever discovered — including The Steinmetz Pink and the Moussaieff Red — representing a dazzling spectrum of color.
This upcoming sale marks only the second time The Ocean Dream has appeared at auction. It last crossed the block at Christie’s Geneva in 2014, achieving $8.8 million. Over the past 12 years, it has remained in a single private collection, adding to its allure.
Today, the diamond is presented in a contemporary ring setting that contrasts its ancient origins. The setting features a geometric constellation of Asscher-cut white diamonds and gold prongs that make the blue-green stone appear to float.
Blue-green diamonds occupy a “niche” category even within the elite world of fancy-color gems, appealing to connoisseurs who recognize their extreme rarity. With no larger Fancy Vivid blue-green diamond known to exist, The Ocean Dream is not just a jewel — it could become an auction phenomenon on May 13.
Credits: The Ocean Dream photos courtesy of Christie’s.