The legendary Mellon Blue diamond, a 9.51 carat fancy vivid blue gemstone of exceptional rarity and pedigree, sold for $25.6 million at Christie’s “Magnificent Jewels” auction in Geneva. The pear-shaped diamond, graded Internally Flawless by the Gemological Institute of America (GIA), drew global attention as one of the headline lots of the season.

Previously owned by philanthropist and arts patron Rachel Lambert “Bunny” Mellon, the diamond carries a rich provenance that further elevated its desirability among collectors. Offered as part of the sale’s marquee lineup, the stone achieved CHF 20.5 million, positioning it among the highest-priced vivid blue diamonds ever sold at Christie’s.

Although the stone previously commanded $32.6 million in 2014, industry experts noted that the latest result reflects a more measured but still robust market, influenced by global economic caution, shifting collector sentiment, and reduced buying activity from some Asian markets. Even so, the sale underscores the enduring value of rare coloured diamonds, particularly those with impeccable clarity and distinguished ownership histories.

The Mellon Blue’s performance adds another significant milestone to Christie’s record in coloured diamonds, reaffirming Geneva’s stature as a leading hub for high-value jewellery auctions.