An Ultra-Rare $30M Blue Diamond Is Coming to Auction this November

Christie’s Auction House

has announced that one of the world’s most extraordinary diamonds is headed to the block: the Mellon Blue. This 9.51-carat Fancy Vivid Blue diamond, graded Internally Flawless, will be the crown jewel of the Magnificent Jewels auction on November 11 at the Four Seasons Hotel des Bergues in Geneva. With an estimate between $20 and $30 million, the Mellon Blue is far more than a dazzling stone—it carries a storied provenance, a touch of mystery, and the kind of rarity that has captivated collectors for generations.

Once worn by the legendary American philanthropist Bunny Mellon, the diamond has already made headlines as one of the highest-priced colored diamonds ever sold at auction. Now, more than a decade after its record-breaking appearance, it returns to the world stage, where it will once again be under the spotlight.