A vivid 12.03-carat diamond dubbed "Blue Moon" was sold in Geneva for a record 43.2 million Swiss francs ($43 million, 40 million euros) on Wednesday, auction house Sotheby's said.

The price was "the highest per carat" ever for this type of precious stone, said David Bennett, head of Sotheby's international jewellery division. The diamond, described as flawless by experts, had an estimated sale price between $35-55 million.