A rare blue diamond sold for $US9.5 million at auction in London on Wednesday, setting a world record for price per carat.
The fancy deep-blue diamond weighing 5.30 carats sold at Bonhams Fine Jewellery sale for a record $US1.8 million per carat, beating the previous record of $US1.68 million.
The diamond is set in a Trombino ring made by Italian jeweller Bulgari around 1965.
It was bought by Graff Diamonds, an international diamond house.
The ABC reports the term "fancy" is used to describe a diamond of intense colour. The blue is derived from small amounts of boron impurities within the diamond.
