LSM is a trade and policy abbreviation for large-scale mining, the category of formally permitted, capital-intensive mineral extraction operated by companies under national mining codes. It is used in contrast to ASM (artisanal and small-scale mining), and the two terms together frame most of the mineral-supply discussion in coloured stones, gold, and diamond. In gemstones the LSM share is dominated by diamond, with significant LSM operations also in tanzanite, emerald (Colombia and Zambia), and sapphire (Madagascar), while ruby and most other coloured stones remain predominantly ASM-supplied.

Definition and scale

The threshold separating LSM from ASM varies by country but generally requires a substantial capital investment, formal mining title, mechanised extraction, and compliance with environmental and labour regulation. The World Bank and OECD estimate that LSM accounts for the majority of global mineral value but employs only a small fraction of the mineral workforce, while ASM is reversed: small share of value, large share of employment. In the diamond industry, named LSM operators include De Beers (Botswana, Canada, Namibia, South Africa), Alrosa (Russia), Rio Tinto (until the 2020 closure of Argyle), Petra Diamonds, Lucara, and Gem Diamonds. In coloured stones, Gemfields plc operates the principal LSM emerald and ruby mines at Kagem (Zambia) and Montepuez (Mozambique).

Trade implications

LSM material typically enters the market through tender or auction systems with documented chain of custody, simplifying sanctions compliance, conflict-free certification, and origin disclosure. The operational scale enables traceability programmes such as Gemfields' provenance data and De Beers' Tracr blockchain platform. Royalty regimes, export taxes, and beneficiation requirements in producer countries (Botswana, Namibia, South Africa) are negotiated principally with LSM operators rather than ASM cooperatives, making the LSM channel central to producer-state revenue.