The London Bullion Market Association, almost universally referred to in the trade as the LBMA, is the international trade body for the wholesale over-the-counter market in gold and silver, headquartered in London. It was founded in 1987, succeeding earlier informal arrangements between London bullion dealers and the Bank of England, and it now functions as the regulatory and standard-setting authority for the bullion industry worldwide.

The LBMA's most consequential outputs for the jewellery trade are its "Good Delivery" lists for gold and silver bars, the "Responsible Gold Guidance" that governs supply-chain due diligence for refiners, and the daily LBMA Gold Price and LBMA Silver Price benchmarks, which are the reference fixings used to settle most physical and over-the-counter contracts in the metals. Refiners on the Good Delivery list are subject to ongoing audit and re-accreditation, and de-listing for sourcing or quality breaches is a regular occurrence rather than a theoretical sanction.

The membership is structured in tiers. Full members include the major bullion banks (HSBC, JPMorgan, ICBC Standard, UBS), refineries (Valcambi, Metalor, Heraeus, Argor-Heraeus, PAMP, Rand Refinery, Tanaka), and a handful of specialist trading houses; associate members include logistics providers, vault operators and consultancies. The Bank of England remains a key counterparty as a vault operator and is closely connected to the LBMA's market-making infrastructure although it is not a member.

For the jewellery trade specifically, the LBMA matters in two ways. First, the price at which jewellers buy refined casting grain or sheet is derived from the LBMA fixing, with refiner premiums layered on top, so the LBMA price is the trade's reference even at the bench level. Second, the Responsible Gold Guidance has become the operational definition of "responsibly sourced" gold for downstream actors including the Responsible Jewellery Council and many luxury houses, so a jeweller buying refined gold from an LBMA-listed refiner has a defensible due-diligence story to their own customers and auditors.