GENEVA (AFP) - A plum-sized diamond known as the "Pink Star" was auctioned in Geneva on Wednesday for US$83 million (S$104 million), a world record for a gemstone.

Mr David Bennett, chairman of Sotheby's jewellery division in Europe and the Middle East, brought down the hammer in a Geneva hotel after an intense, five-minute bidding race.

The winning bidder, a bearded man apparently in his 60s sporting a Jewish skullcap, was pitted in a one-on-race against a telephone competitor.

The bidding in Geneva was conducted in Swiss francs, starting at 48 million (S$65 million) and working its way upwards million-by-million.

There was a long silence as the price reached 67 million Swiss francs, before the in-room bidder came back with the winning 68 million.

Commission included, the final price was 76 million francs - the equivalent of $83 million.

There were up to 150 people in the auction room who erupted into applause as the theme tune from the "Pink Panther" was played as a tongue-in-cheek gesture.

The winning bidder declined to identify himself to Agence France-Presse but confirmed that he had been representing another individual, whose name and location he refused to reveal.

The diamond had been estimated at US$60 million.

Three years ago, Sotheby's set an auction record of US$46.2 million - commission included - for a diamond when it sold the "Graff Pink" gemstone.