One of the most anticipated jewelry auctions in recent years—Christie’s Magnificent Jewels—took place on November 11, 2025, at the Four Seasons Hotel des Bergues in Geneva. The star of the event was the famous 9.51-carat Mellon Blue diamond. The stone is classified as Fancy Vivid Blue, Internally Flawless (IF). Exceptionally rare, it once belonged to American philanthropist and collector Rachel “Bunny” Mellon. Experts describe it as a “jewel among jewels,” mainly because of its extraordinary color saturation and perfect clarity. The auction attracted collectors from around the world, while Christie’s emphasized that the Mellon Blue is one of the finest colored diamonds ever to appear on the market.
The price surprised experts – a drop in value after 11 years
Despite the tremendous interest and prestige surrounding the auction, the final sale price was 20.5 million Swiss francs. In other words—about $26.6 million (108 million PLN). This amount was within the pre-auction estimates. However, it came as a surprise to the luxury gemstone market—in 2014, the same diamond, also auctioned by Christie’s after Bunny Mellon’s death, fetched over $32 million. This represents a drop in value of nearly 17%, even though in recent years the colored diamond market was considered exceptionally stable, if not growing.
Experts point to several reasons for this difference. First, the global luxury goods market in 2025 felt the impact of declining demand in Asia and shifting investor preferences. Increasingly, investors are choosing art and watches over precious stones. Second, more diamonds in the Fancy Vivid Blue category have recently appeared at auctions, which has diminished their uniqueness. Finally, the Mellon Blue was presented as a ring, which for some collectors may have limited its investment flexibility.
A gem with a unique story
Despite its lower price, the Mellon Blue remains one of the world’s most highly regarded diamonds. Its color—a deeply saturated, cool shade of blue—and flawless crystal structure make it a global rarity. For decades, the stone was part of Bunny Mellon’s private collection, renowned for her impeccable taste and passion for art, gardening, and jewelry. Christie’s described the sale of the Mellon Blue as an event “of both prestige and symbolic significance.”
Although the auction result did not break the 2014 record, the transaction confirmed one thing – demand for top-quality colored diamonds remains strong. Meanwhile, the Mellon Blue continues to shine as one of the most beautiful blue gems ever unearthed.
