Rare ‘Mellon Blue’ Diamond Fetches $25.5 Million at Christie’s Geneva – Market Reflects Shifting Demand for Coloured Diamonds

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.

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‘The Mellon Blue’ Diamond Set to Shine at Christie’s Geneva Auction

Christie’s is preparing to present one of the most important diamonds to appear at auction in recent years – The Mellon Blue. Estimated at $20 million to $30 million, the 9.51-carat fancy vivid blue pear-shaped diamond will headline the Geneva Magnificent Jewels sale on 11 November at the Four Seasons Hotel des Bergues.

If it reaches the top of its estimate, The Mellon Blue will once again secure its place among the world’s most valuable fancy blue diamonds.

A Rare and Flawless Gem

This remarkable diamond is graded Internally Flawless, and its vivid colour saturation and elegant pear shape make it one of the finest fancy blue diamonds to come to market this year. It has been mounted at the tip of a diamond-paved swirl ring, highlighting its exceptional fire and brilliance.

Provenance: Bunny Mellon

The diamond takes its name from Rachel “Bunny” Mellon (1910–2014), the renowned American philanthropist, horticulturalist, and art collector. Mellon, who designed the White House Rose Garden for President John F. Kennedy, was equally admired for her refined taste in jewellery.

Her estate sale at Sotheby’s in 2014 achieved an extraordinary $218 million, with the jewellery collection alone fetching more than $45 million. Among the highlights of that auction was this very diamond, then weighing 9.75 carats and sold as the “Zoe Diamond,” which realised $32.6 million – setting world records for both price per carat and overall price for a blue diamond at auction.

Returning to the Public Eye

Now renamed The Mellon Blue in honour of its most celebrated owner, the diamond will be unveiled to the public in Hong Kong (23–28 October) and Geneva (7–11 November) ahead of the sale. Christie’s has also announced that the Geneva auction will feature important jewels by Harry Winston, Cartier, JAR, and Van Cleef & Arpels.

Rahul Kadakia, Christie’s International Head of Jewellery, commented:

“This stunning fancy vivid blue diamond, once belonging to America’s ‘Garden Queen,’ is among the finest coloured diamonds to appear for sale at auction. We look forward with great anticipation to its return.”

The November 11 auction of The Mellon Blue will conclude a week-long series of high-profile jewellery and watch sales in Geneva.

Source: DCLA