The legendary Mellon Blue Diamond a 9.51-carat fancy vivid blue, internally flawless gem sold for $25.5 million USD at Christie’s Magnificent Jewels auction in Geneva this week. The sale, held at the Four Seasons Hotel des Bergues, drew global attention from elite collectors and gem enthusiasts alike.
The Mellon Blue once belonged to renowned art collector Rachel Lambert “Bunny” Mellon, whose refined taste and cultural influence continue to shape the world of art and jewellery. Despite its exquisite pedigree, the price achieved represents a 22 percent decrease from its previous sale 11 years ago and a nearly 60 percent drop in real value when adjusted for inflation.
Originally auctioned at Sotheby’s in 2014 as part of Mellon’s estate collection, the diamond fetched $32.6 million USD, setting a world record for a blue diamond at that time. Adjusted for inflation, that sum equates to approximately $44.7 million in 2025.
Christie’s had estimated the gem between $20 million and $30 million, and the final sale once again highlighted the continuing prestige of exceptional coloured diamonds despite softer market conditions.
Rahul Kadakia, Christie’s Chairman of Global Luxury and President of Asia Pacific, remarked:
“It was a true honour to offer for sale the exquisite Mellon Blue Diamond here at Christie’s Geneva. It was another notable moment for Christie’s Luxury, evidencing the elite appetite amongst collectors for extraordinary and storied gems.”
The winning bidder, identified only as a collector from Hong Kong, continued the stone’s legacy of global fascination.
While the Mellon Blue once held the world record for a blue diamond, that benchmark has since been overtaken by two other remarkable stones:
- The 14.62-carat Oppenheimer Blue, sold at Christie’s in 2016 for $57.5 million USD
- The 15.10-carat De Beers Cullinan Blue, sold by Sotheby’s in 2022, also for $57.5 million USD
These historic sales underline the rarity and enduring appeal of fancy vivid blue diamonds, which represent less than 0.1 percent of all diamonds, and of those, fewer than 1 percent qualify as fancy vivid.
Bunny Mellon, who passed away in 2014 at age 103, was celebrated not only for her wealth being heiress to the Listerine and Mellon fortunes but also for her artistry and impeccable taste. She famously designed the White House Rose Garden and curated an impressive art collection that included two Rothko masterpieces, which together realised $76 million USD at auction.
When Christie’s announced the diamond’s return to auction earlier this year, Kadakia described the sale as a tribute to Mellon’s lasting influence, saying her legacy “elevates the Mellon Blue’s allure by tying it to her sophisticated aesthetic and cultural prominence.”
The auction itself was as heated as the competition literally with the auctioneer requesting the windows be opened mid-sale to cool the room as bidding intensified.
About DCLA: The Diamond Certification Laboratory of Australia (DCLA) is the official CIBJO-recognised diamond laboratory in Australia, specialising in independent diamond grading and certification. DCLA ensures the highest international standards of accuracy, integrity, and transparency in diamond evaluation.