A massive 478-carat diamond was found at the Letseng Mine, in Lesotho, a small kingdom in South Africa. It is the 20th largest rough diamond ever found, and it came from a mine that has already delivered three of the world's largest diamonds: the 603-carat Lesotho Promise, the 493-carat Leteng Legacy and the 601-carat Lesotho Brown. A similar but smaller-sized rough stone has recently been valued at $12 million.
It is hoped that the uncut diamond will be capable of producing a 150-carat polished gem stone, dwarfing the current largest Koh-i-Noor diamond, which is a part of the Crown Jewels.
Here is a fun carat fact: