Flawless blue diamond, the most expensive gemstone in the world, sells at auction for £4m
Blue diamond ~ 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.