World biggest polished diamond

In photo is the world's 20th largest rough diamond. In the proper hands the 478-carat stone could become the biggest polished, round diamond in history and weigh some 150 carats. Experts say the stone is of top-quality color and clarity and could fetch tens of millions of dollars. Miners unearthed the stone at Gem Diamonds' Letseng mine, a facility in which the Lesotho government holds a 30 percent share.