The Letseng Diamond Mine, located in the Maluti Mountains, Lesotho, is the highest diamond mine in the world at an average altitude of 3 100m above sea level and is one of the coldest places in Africa.
Letseng is characterized by extremely low grade ore (less than 2 cpht) and is well known for producing large diamonds, having the highest percentage of large diamonds (greater than 10.8 carats) of any kimberlite diamond mine, giving it the highest dollar value per carat of any kimberlite diamond mine.
Letseng diamond mine is operated by Letseng Diamonds joint venture, 70% owned by Gem Diamonds in partnership with the Government of the Kingdom of Lesotho, which owns the remaining 30%. 
Previously Letseng was operated by De Beers between 1977 and 1982, Letseng reopened operations in 2004 and was acquired by Gem Diamonds in late 2006 for US$118.5 million.
Letseng processes ore from two kimberlite pipes as well as from existing stockpiles. The mine has the capacity to treat some 7 million tonnes of ore annually, which would produce approximately 100 000 carats.