The Letseng Legacy is a 493-carat gem-quality rough diamond recovered on 28 September 2007 at the Letseng-La-Terae mine in Lesotho, operated by Gem Diamonds Ltd. The stone is a Type IIa - chemically pure, nitrogen-free - and is one of an exceptional series of plus-100-carat diamonds produced at Letseng since the mine's revival under Gem Diamonds in 2003. It was sold by Letseng Diamonds for U.S. $10.4 million in October 2007, equivalent to approximately $21,000 per carat, then a record price per carat for a rough diamond above 200 carats.

Recovery and sale

The Letseng Legacy was recovered through Letseng's standard kimberlite processing circuit - the mine, despite operating at an unusually low grade of approximately 1.5 to 2 carats per hundred tonnes, is engineered with large-stone recovery in mind, including XRT (X-ray transmission) and dense-media separation circuits designed to identify and divert plus-50-carat material before it can be damaged by crushing. The 493-carat rough emerged intact from the recovery process and was the second of two exceptional Letseng stones in 2007, following the 603-carat Lesotho Promise recovered in August of the same year.

Gem Diamonds offered the Letseng Legacy on the Antwerp tender market in October 2007, and it was sold to a partnership of South African (SAFDICO) and other manufacturers for $10.4 million. The price reflected both the exceptional Type IIa quality and the active 2007 large-stone market.

Cutting

The buyer announced that the rough would be cut into a series of polished diamonds at the SAFDICO and partner facilities. The largest polished stone produced from the rough was approximately 75 carats, with multiple smaller satellite diamonds cut from the surrounding rough. Specific final yield figures and the disposition of individual cut stones are private; the Letseng Legacy series has not been publicised to the same extent as the Graff Lesedi La Rona series of the late 2010s.

Position in the Letseng record

The Letseng Legacy is one of the principal stones in the Letseng-La-Terae historic record, alongside the 1967 Lesotho Brown (601 ct), the 2006 Lesotho Promise (603 ct), the 2011 Letseng Star (550 ct), the 2018 Lesotho Star (550 ct), and over twenty other plus-100-carat recoveries since 2006. The combination of these recoveries has defined Letseng's modern reputation as the world's most prolific source of large gem Type IIa diamonds, and the Letseng Legacy specifically marked an important early demonstration that the mine could produce plus-200-carat goods on a recurring basis under modern operational conditions.