GENEVA (AFP) - A 15.38-carat vivid pink diamond, the biggest of its kind to go on auction, was sold for a new record total of US$31.56 million ($43.2 million), Sotheby's auction house said Tuesday.

Two telephone bidders battled for the prized jewel before some 150 people attending the auction held at a luxurious hotel in Geneva.

"It's a new world record... It's the highest price ever paid for a fancy vivid pink diamond," said auctioneer David Bennett.

He added only that the buyer was a private individual from Asia.

Sotheby's had valued the "exceptional" pear-shaped diamond, mounted on a ring, at between US$28-38 million.

It was discovered less than five years ago in a South African mine.

The seller was the New York-based company Cora International.

The stone with the name "Unique Pink" was certified a fancy vivid pink diamond, the most sought after colour in pink diamonds, by the Gemmological Institute of America.

Also on Tuesday Sotheby's sold a blue diamond, weighing 7.32 carats, for US$17.1 million.

On Wednesday, the magnificent spring jewel auctions continue in Geneva with what Christie's says is the biggest-ever vivid blue diamond to go on the auction block.

The 14.62-carat blue diamond, known as the "Oppenheimer Blue", is estimated at between US$38-45 million.

The jewel belonged to Britain's Sir Philip Oppenheimer (1911-1995), a kingpin in the world diamond market for nearly 50 years at De Beers.