A blue diamond that was once part of De Beers Millennium Collection sold for US$ 6.4 million at an auction held by Sotheby’s in Hong Kong yesterday, in a 12-gem sale that raised US$ 52.4 million overall. The giant diamond producer, celebrating the new millennium, presented the 5.16-carat pear-shaped gem in 2000. Auctioneers were expecting to raise between US$ 4.6 million and US$ 5.8 million with it, but the gem exceeded expectations. The beautiful blue diamond is pictured below.