Diamonds were discovered in Sierra Leone in 1930, and in 1934
sole mining rights were granted to the Sierra Leone Selection Trust
(SLST), a subsidiary of the London-based Consolidated African
Selection Trust, part of De Beers empire. In 1956, partly to restrict
the increasingly prevalent illicit mining, and partly for political
reasons, SLST opened part of its lease to mining by licensed miners
under the Alluvial Diamond Mining Scheme (ADMS). The Sierra Leone
government took over 51 per cent of the SLST shares in 1970, and a new
company, the National Diamond Mining Company (NDMC), was formed. In
1980 SLST sold out to British Petroleum and left Sierra
Leone.
