The Letseng diamond mine, found in the landlocked Southern Africa

Southern Africa

Southern Africa is the southernmost region of the African continent, variably defined by geography or geopolitics. Within the region are numerous territories, including the Republic of South Africa ; nowadays, the simpler term South Africa is generally reserved for the country in English.-UN...

n kingdom of Lesotho

Lesotho

Lesotho , officially the Kingdom of Lesotho, is a landlocked country and enclave, surrounded by the Republic of South Africa. It is just over in size with a population of approximately 2,067,000. Its capital and largest city is Maseru. Lesotho is a member of the Commonwealth of Nations. The name...

, is owned by Gem Diamonds

Gem Diamonds

Gem Diamonds is a leading British-based global diamond mining business. It is headquartered in London and is a constituent of the FTSE 250 Index.-History:...

, 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.

Production

It is characterised by extremely low grade ore (less than 2 carats (400 mg)/hundred tons) and is well known for producing huge diamond

Diamond

In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...

s, having the highest percentage of large diamonds (greater than 10 carats (2 g)), giving it the highest dollar value per carat of any diamond mine. The world average is roughly US$

United States dollar

The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....

81 per carat, while Letseng 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.

Lesotho Promise

On the 4th of October 2006 the 603 carat (121 g) white diamond, the Lesotho Promise was unearthed, and is the largest reported find this century and the 15th largest diamond ever found. The stone is an exceptional colour, rated D, the top colour for diamonds.

Lesotho Brown

Previously the largest diamond found at Letseng was the 601 carat (120 g) Lesotho Brown, recovered in 1967.

Letseng Legacy (September 2007)

On September 13, 2007 Gem Diamonds, Ltd. announced that it found a 493 carats (98.6 g) diamond, making it the 18th largest diamond ever found. It was sold to the Graff-SAFDICO partnership for $10 million.

Star of Lesotho

In 2004, Gem Diamonds, Ltd. found a large diamond of 123 carats (24.6 g).

Leseli La Letšeng (September 2008)

On September 21, 2008 Gem Diamonds, Ltd. announced that it found a 478 carats (95.6 g) diamond of high quality, making it the 20th largest diamond ever found. It is a type II D colour, with potential to yield a 150 carats (30 g) cut stone. Chief executive Clifford Elphick said: "Preliminary examination of this remarkable diamond indicates it will yield a record-breaking polished stone of the very best colour and clarity, and has no inclusions visible in its rough form."

November 2010

The discovery of two large rough white diamonds was announced in November 2010. They weighed 196ct and 184ct.