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 Sotheb

While the Christie's auction starting 16th of October will embrace magnificent jewels from all around the world, an 8ft (2.5 meter) sculpture of a diamond by US artist Jeff Koons is anticipated to fetch around $12m (£6m) when it is sold at Christi