‘Mellon Blue’ diamond sells for $25.6 million at Swiss auction

Rare Blue Diamond Fetches $25.6 Million at Christie’s Geneva Auction

The “Mellon Blue,” a rare pear-shaped blue diamond weighing 9.51 carats, sold for 20.5 million Swiss francs ($25.6 million) at a Christie’s auction in Geneva on Tuesday. The final price, which includes buyer’s premium and additional fees, fell within the pre-auction estimate of $20-30 million.

Named after the late American arts patron Rachel “Bunny” Mellon, the exceptional stone was part of her private collection for decades before first being sold at auction in 2014, the year of her death, for $32.6 million—one of the highest prices ever paid for a colored diamond at that time.

Market analysts noted the sale was somewhat subdued compared to expectations. Tobias Kormind, managing director of online jeweler 77 Diamonds, commented on the auction atmosphere: “Not the dazzling moment I expected. Geopolitical tensions—from the war in Ukraine to Trump’s tariffs—and a weakened Chinese economy that kept many usual buyers away, left the room distinctly cautious.”

The diamond’s selling price represents a notable decrease from its previous auction value, potentially reflecting broader economic uncertainties in the luxury market. Despite this, Christie’s auctioneer Rahul Kadakia, chairman of the global luxury group, emphasized the significance of the sale as a “notable moment” that demonstrates “the elite appetite among collectors for extraordinary and storied gems.”

What makes the Mellon Blue particularly remarkable is its classification as Fancy Vivid Blue and Internally Flawless by the Gemological Institute of America—the highest possible grading for colored diamonds. Max Fawcett, Christie’s global head of jewelry, highlighted the stone’s exceptional nature, explaining that unlike the majority of modern gems that undergo faceting modifications to enhance color, the Mellon Blue maintains its natural qualities.

“When you have great shape and great color, you’re looking at the gem of gems,” Fawcett remarked. “That’s what this is.”

While impressive, the Mellon Blue sale falls considerably short of the record price for a blue diamond. That benchmark was set in Geneva in 2016 when Christie’s sold the 14.62-carat Oppenheimer Blue for more than $57 million.

The auction took place during a significant week for high-value colored diamonds in Geneva. Rival auction house Sotheby’s is set to offer the “Glowing Rose” pink diamond on Wednesday, with expected bids around $20 million, continuing the season of ultra-luxury gem sales.

Blue diamonds derive their color from the presence of boron during their formation deep within the Earth’s crust. They rank among the rarest and most valuable colored diamonds in the world, with only a handful of significant specimens appearing at auction each decade.

The market for colored diamonds has traditionally been resilient even during economic downturns, as these stones are viewed not just as jewelry but as investment assets with historical significance