Roughly equivalent to a quail's egg in size, it took two years to cut and is the biggest such diamond ever to have been put up for sale at auction.

That is just short of the all-time auction record for a stone or piece of jewelry, a record held by the same Sotheby's branch in Geneva for a 100.1-carat diamond that fetched $16.5 million in 1995.

The diamond has received the highest possible grading, Sotheby's said. It is D-colour, or finest white, has flawless clarity, and its cut, polish and symmetry have all been graded excellent.

The New York-based company is hoping the "Magnificent Jewels" sale at Geneva's historic Beau Rivage hotel will help it bounce back from the disheartening results of its impressionist and modern art auction, which sent its stock tumbling.

The sale last week fetched $269.7 million, well short of estimates, and led some analysts to speculate whether the flight from risk currently gripping financial markets may be spilling over into the art world.

The company announced that it lost $14.6 million by purchasing paintings that failed to sell.

The white diamond has already been showcased in Hong Kong, Paris, New York, Rome, Los Angeles, London, Dubai and Bahrain. The auction Wednesday also featured other diamonds, coloured stones and gems from the world's leading jewellers.

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