Premier Blue

"Premier Blue"is hitting the market today. At 7.59 carats and brilliant-cut, it's considered the world's biggest blue round diamond. Blue diamonds seldom hit the market and have been coveted by royals and celebrities for centuries, while a round cut is rarely used in coloured stones because of the high wastage.  It's estimated to sell for more than $19 million at an auction in Hong Kong.

photo via ahametals