Letšeng Diamonds is a diamond mining company situated 3,100 meters above sea level, high in the Maluti Mountains in the Kingdom of Lesotho, southern Africa. Letšeng Diamonds is owned by Gem Diamonds Limited (70%) and the Government of Lesotho (30%) and was granted the mining lease in 1999. The mine produces diamonds which sell for the highest per carat price of any kimberlite mine.

The mine, which has been in commercial operation since 2004, has a total processing capacity of over 5 million tonnes per year and recovery of approximately 100 000 carats per year, which makes Letšeng Mine the seventh largest kimberlite mine in the world.

90 percent of diamonds recovered are gem quality, with a significant proportion graded as D colour. Over 70 percent of revenue is from diamonds in excess of 10,8 carats. The mine has produced several diamonds over 400 carats and numerous stones over 100 carats.

Letšeng Diamonds has recovered three of the world's top twenty rough diamonds. These include the 603 carat Lesotho Promise in August 2006, the 493 carat Letšeng Legacy in September 2007 and the 478 carat Leseli la Letšeng in September 2008. The 601 carat Lesotho Brown found in 1967 came from the Letseng Mine.

Letšeng's average value per carat at approximately US $1 600 is almost (16) times the industry average. The mine also has the highest percentage of large diamonds (over 10 carats) of any known kimberlite mine, while having relatively low carat weight per ton of ore production.

Apart from the normal benefits derived from the company's tax contributions, the mine currently employs around 1000 people. Over 80% of all goods and services are acquired locally. Up to 45% of growth in GDP has been attributed to the mining industry.