Lesotho digs up another huge gem Khotso Maama Maseru – The world’s highest dollar-per-carat mine, Lesotho’s Letšeng Diamonds, has unearthed another mega gem, this time a high quality 370-carat Type II white diamond. YOU MAY ALSO LIKE Gem Diamonds, which owns 70 percent of Letšeng Diamonds with the remainder being held by the Government of Lesotho, said the find followed another of a high quality 254-carat Type II white in early May. “Gem Diamonds Limited is pleased to announce the recovery of a high quality 370-carat Type II white diamond from the Letšeng Mine in Lesotho, the highest dollar-per-carat kimberlite diamond mine in the world,” the company said this week.