An exceptional Fancy Vivid Blue diamond, weighing 9.51 carats, is up for sale at Christie’s. It’s The Mellon Blue, the auction house’s first flagship jewel of the second half of 2025. The stone is graded Internally Flawless and is set as a ring. The diamond will be sold in the Magnificent Jewels sale to be held on November 11th at the Four Seasons Hotel des Bergues in Geneva. This type of diamond is particularly rare, and this specimen is remarkable for both its intense color and its extraordinary clarity.
How much is it worth? Experts estimate it between $20 and $30 million. Its name comes from the fact that for decades the stone, set as a pendant, belonged to Rachel Lambert Mellon, better known as Bunny Mellon (1910–2014), a wealthy American philanthropist and art collector. The Mellons are a wealthy and influential American family from Pittsburgh, Pennsylvania, active in banking, finance, business, and politics. Bunny Mellon was a symbol of elegance and refinement. The diamond was last seen publicly in 2014, when it was offered at auction in New York, achieving one of the highest prices ever paid for a colored diamond at auction.
Christie’s sold nine of the top ten jewels at auction in the first half of the year, with a 25% year-over-year increase, with two separate owner-led live auctions achieving 100% sales in New York and Geneva. We now look forward to the second half of 2025 with confidence as we announce The Mellon Blue. This stunning Fancy Vivid Blue diamond, once owned by the American Garden Queen, is among the most valuable colored diamonds ever offered for sale at auction.
Rahul Kadakia, International Head of Jewelry at Christie’s
