Bunny Mellon’s Exceptional Blue Diamond Expected to Fetch Up to $30 Million at Auction

The 9.51-carat pear-shaped diamond that once belonged to Rachel Lambert “Bunny” Mellon is headed to auction this November, with an estimated sale price of $20,000,000 to $30,000,000. Leading Christie’s Magnificent Jewels sale, which will take place on November 11 at the Four Seasons Hotel des Bergues Geneva, The Mellon Blue is touted for its intense color and purity.

“Christie’s has sold nine of the top 10 jewels at auction in the first half of the year, driving year-on-year growth by 25%, with two various owner live auctions selling 100% in New York and Geneva,” says Rahul Kadakia, Christie’s International Head of Jewelry. “We are now looking confidently to the second half of 2025 by announcing ‘The Mellon Blue.’ This stunning Fancy Vivid Blue Diamond, once belonging to America’s Garden Queen, is among the finest colored diamonds to appear for sale at auction.”

Under Mellon’s ownership, the jewel, graded as Internally Flawlesss, was set as a pendant. It was last seen publicly in 2014, when it was offered by Sotheby’s as part of The Collection of Mrs. Paul Mellon sale. Mellon, who died in 2014, is a revered American horticulturist and socialite who designed the White House Rose Garden for her good friend Jacqueline Kennedy. Her legacy and influence on gardening and design was also recently celebrated in a special pop-up exhibition at London’s Garden Museum.

Before the sale, “The Mellon Blue” will be on view at Christie’s Hong Kong and the Four Season Hotel des Bergues Geneva.