This is one of the rarest gems in the world - a 6.04 carat diamond that is fancy vivid blue color and has internally flawless clarity. The expensive stone was bought by a British jeweler for a record-breaking sum of almost £4 million at a Sotheby’s auction in Hong Kong. The selling price makes it the most expensive gemstone in the world, per carat, sold at any auction. The flawless blue diamond fetched £650,000 per carat after intense bidding. It also broke 20-year-old record that was held by the Hancock Red, a red diamond which fetched £450,000 per carat at the time. The seller of the extremely rare diamond was a private Asian collector while the buyer was Moussaieff Jewellers in London.

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