Diamond could yield one of the largest and highest quality round polished stones . The diamond is a very hard material, so it can be cut with a knife or other cutting instrument without damaging its surface. Diamond found in Letseng Mine , in Lesotho .
Diamond could yield one of the largest and highest quality round polished stones . 478-carat stone determined it to be of the highest color grading available . Diamond found in Letseng Mine , in Lesotho .