Geneva  - A rare blue diamond fetched a world record 9.3 million Swiss francs (8.4 million dollars) at an auction by Sotheby's in Geneva on Tuesday.

The cut and polished gem weighing 7.03 carats was sold by Cullinan Mine in South Africa to an as yet unknown telephone bidder, who will also pay a buyer's premium.

The diamond was cut from an original blue diamond of 26.58 carats and was naturally coloured and internally flawless, Sotheby's said. (dpa)