A 14.62 carat blue diamond is expected to fetch a record $45m (£31m) at this week’s Magnificent Jewels auction in Geneva.
Estimated between $38m and $45m, the rectangular-cut diamond is the largest of its kind to be offered at auction and has been graded as “fancy vivid blue”, meaning its blue colour ranges from medium to dark in tone, and from strong to very strong in saturation.
It previously belonged to the late Sir Philip Oppenheimer, who began work in the family business at De Beers in 1934 and went on to control the Diamond Syndicate in London.
As chairman for the Diamond Trading Organisation, Oppenheimer, who died in 1995, tightly controlled the international diamond trade and helped make it extremely lucrative.
Christie’s have valued the Oppenheimer stone at between $38m and $48.4m, giving it an outside shot at breaking a record set by rival auction house Sotheby’s in November.
The 12.03 carat Southeby’s diamond, named The Blue Moon of Josephine, was bought for $48.4m by Hong Kong billionaire Joseph Lau, who a day earlier scooped up a 16.08 carat pink diamond for $28.5m.
According to Christie’s, the Oppenheimer is the largest ever sold at auction in the exclusive Fancy Vivid Blue category, which groups rare gems of exceptional colour and clarity.
Christie’s has valued its total of 280 lots up for auction at $113m (£77m). The collection includes 46 pieces from German-born princess Gabriela zu Leiningen, who was married to the Aga Khan.