Approximate cost of a one-carat blue diamond?

A natural blue diamond is a rare diamond and will be very pricey. In April 2010, a five-carat vivid blue stone was auctioned in Hong Kong with estimated bidding to range between US$4.6-$5.8 million.

In May 2009, Sotheby's Geneva auctioned a 7.03 carat, internally flawless, fancy vivid blue stone for US $9.48 million.

Read more about these stones, below.