Giant diamond sells for more than $12 million By Elizabeth Boswell Mon Oct 9, 11:11 AM ET ANTWERP, Belgium, Oct 9 (Reuters Life!) - The biggest diamond to be found in 13 years, the "Lesotho Promise," was sold on Monday at auction for more than $12 million and is expected to fetch in excess of $20 million once it is cut up. The 603-carat (120 gram) diamond, named after the tiny African mountain kingdom where it was found, went under the hammer at the Antwerp Diamond Center and was sold to the South African Diamond Corporation, owner of luxury jewellers Graff. The 10th largest white diamond ever to be found, it will be cut into a large heart-shaped diamond and several smaller stones which will then be sold. The uncut diamond is a third bigger than a golf ball. Johnny Kneller from the South African Diamond Corporation said that once it was cut up, he expected to sell the stones for a third more than the auction price. "We can't say for sure but we hope it's going to fetch over $20 million," Kneller said. Diamonds have long been a status symbol and were famously serenaded as a girl's best friend by Marilyn Monroe in the 1950s film "Gentlemen Prefer Blondes." Growing affluence has boosted sales and busy shopping streets such as London's Bond Street are awash with jewellers and luxury goods stores offering right-hand diamond rings for well-heeled women. The biggest rough diamond ever found was the Cullinan at 3,106 carats, while the second largest, the Excelsior, was 995 carats. Both were found in South Africa. The Lesotho diamond was found at the Letseng Diamond Mine high in the mountains of the tiny nation which is surrounded by South Africa, by a woman who was sorting through the rocks. "She started screaming and all the staff thought she had been electrocuted," said Clifford Elphick, head of Gem Diamond Mining, which owns 70 percent of the mine. He said he was very pleased with the price that the gem had fetched.