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

One the rarest gems in the world has has been snapped up by a British jeweller for a record-breaking sum of almost £4million.

One of the rarest gems in the world, a flawless blue diamond, has sold for £4 million at a Sotheby's auction in Hong Kong.

This makes it the most expensive gemstone in the world, per carat, sold at auction.

After intense bidding, the 6.04 carat, internally flawless blue diamond fetched £650,000 per carat.

The price smashed a 20-year-old record held by the Hancock Red - a red diamond which fetched £450,000 per carat at the time, Sotheby's said.