A blue diamond, the largest of its kind in the world, has been sold at auction in Geneva for CHF21.4 million ($24 million) to US jeweller Harry Winston, taken over earlier this year by Switzerland’s Swatch Group.

The seller of the flawless pear-shaped gem, known simply as “The Blue”, wished to remain anonymous. Swatch had announced after its purchase of Harry Winston that it wished to increase the jeweller’s diamond portfolio to meet international demand.

The pear-shaped stone had been estimated at up to CHF22.5 million. It weighs 13.22 carats and was the highlight of Christie’s auction on Wednesday, at which 217 objects were sold for a total of CHF138.9 million.

Six months ago, the auction house sold in Geneva a 14.82-carat orange diamond for the record price of CHF31.2 million.

Also on Wednesday, rival Sotheby’s said its spring auction had sold a world record $141.5 million (CHF126 million) in jewellery.

The auction house said seven records in all were set at the Geneva auction including the highest amount ever paid for a yellow diamond – $16.3 million for the 100.09-carat “Graff Vivid Yellow” diamond ring.

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