The Letšeng Diamond Mine, found in the landlocked Southern African kingdom of Lesotho, is owned by Gem Diamonds, Ltd. and the government of Lesotho, and at an elevation of 3,100 m (10,000 ft). It is the world's highest diamond mine.

It is characterised by extremely low grade ore (less than 2 carats (400 mg)/hundred tons) and is known for producing huge diamonds, having the highest percentage of large diamonds (greater than 10 carats (2.0 g)), giving it the highest dollar value per carat of any diamond mine. The world average is roughly US$81 per carat, while Letšeng averaged over US$1,894 per carat for the first six months of 2007.

Unusual for Africa, and due to the elevation, temperatures at the mine drop to -20 °C, and snowfalls are common in winter.

Letšeng has a tundra climate (ET, according to the Köppen climate classification), with an average annual precipitation of 881 mm (35 in). This climate has chilly to cold temperatures throughout the year, with snowfalls.