epa12510115 A Christie's employee displays the Mellon Blue, a fancy Vivid Blue pear-shaped cut diamond of 9.51 carats, during a preview at the Christie's auction house in Geneva, Switzerland, 07 November 2025. The piece will be auctioned in Geneva on 11 November 2025. EPA/MARTIAL TREZZINI 
By Cecile Mantovani
The internally flawless pear-shaped diamond mounted at the tip of a swirling ring design is named the "Mellon Blue," after its former owner who had it set as a pendant. It sold for $32.6 million in 2014, the year Mellon died at the age of 103.
That was the highest price at the time ever paid for a coloured diamond at auction, Christie's said. But the world record for a blue diamond is the "Oppenheimer Blue," which sold for over $57 million in Geneva in 2016.
Mellon, an avid, self-taught horticulturalist, came from a wealthy background and married into the Mellon banking family.
One of her legacies was a redesign of the White House Rose Garden during the Kennedy administration, which U.S. President Donald Trump again renovated this year.
(Reporting by Cecile Mantovani; Writing by Emma Farge; Editing by Richard Chang)