Bunny Mellon’s Most Mysterious Diamond
Few jewels connect American cultural history and the contemporary auction market as precisely as the Mellon Blue. Once owned by Rachel Lambert “Bunny” Mellon, the 9.51-carat Fancy Vivid Blue pear-shaped diamond returned to auction at Christie’s Geneva on 11 November 2025, carrying an estimate of $20 million to $30 million. It realised $25.592 million, becoming the third-highest price achieved for a vivid blue diamond at Christie’s.
Mellon was an American horticulturalist, philanthropist and art collector whose taste extended across gardens, interiors, art and jewellery. In 1961, John F. Kennedy asked her to redesign the White House Rose Garden, while her private collection included works by figures such as Fulco di Verdura and Jean Schlumberger. After her death in 2014, more than 1,500 objects from her personal collection were offered at auction in New York. The Mellon Blue was among the defining jewels, appearing as a pendant and carrying the discreet provenance of a collector whose public life was considerably better documented than her private one.
The diamond first appeared at auction at Sotheby’s New York on 20 November 2014, where it sold for $32.6 million and set a world record for a blue diamond. It then weighed 9.75 carats and was mounted as a pendant. After the sale, the stone was retouched, altering its weight to 9.51 carats, and reset in a serpentine pavé platinum ring engraved “Fancy Vivid Blue”. Its 2025 GIA report records Fancy Vivid Blue colour, VVS1 clarity, potentially Internally Flawless, and Type IIb classification.
What distinguishes the Mellon Blue is not simply its auction history, but the restraint of its provenance. Little is known about when Mellon acquired the stone or how often she wore it. That absence of detail sits naturally beside a collector known for gardens, interiors and objects selected with precision rather than display. In Geneva, the diamond entered a market increasingly defined by rarity, provenance and cultural recognition, moving from Mellon’s private world into the contemporary language of collecting.
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