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Gold refining turns doré—a variable-purity alloy made by processing and smelting mined ore—into gold separated to a specified fineness, then cast into forms suited to particular markets. The steps and final purity vary by refinery, feedstock and customer requirements. “Investment-grade” is not the same as “London Good Delivery”: that designation applies to bars meeting a specific wholesale-market standard, not every product from an accredited refiner.
What gold doré is—and why it must be refined
Doré is an alloy bar made from newly mined gold after ore has been processed and smelted to concentrate its metals. LBMA defines it as generally 85%–90% pure, but that is a typical description, not a guaranteed intake specification for every refinery. The Royal Canadian Mint, for example, says its pre-melt stage handles doré bars containing about 70% gold. The difference illustrates why a refinery assays incoming material rather than assuming a fixed composition.
Doré is not finished bullion: it contains gold along with other metals, and its precise composition affects how much fine gold is present. An assay measures that composition. The measured weight and fine-gold content help establish the material’s payable value and guide its processing.
Sources: LBMA’s definition of doré and the Royal Canadian Mint’s refining overview.
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How a refinery turns doré into refined gold
The exact route depends on the feedstock and the refinery’s process and customer specification. At a high level, the material is received and weighed, melted, sampled for assay, and processed to separate gold from unwanted metals. The assay provides a measured basis for determining the composition and value of the batch; it is not simply a label based on the mine or bar’s origin.
The Royal Canadian Mint describes pre-melt and assay stages and says its process refines gold from a standard 99.5% to exceptional purity of 99.999%. Those figures describe the Mint’s refining capability, not a universal range or required endpoint for every refinery. Different output specifications serve different uses.
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After refining, the metal can be cast into products for different customers and markets. The Mint lists investment products and collectible coins among its gold outputs. A refinery’s output therefore need not be a wholesale bar, and a refinery’s accreditation does not by itself confer a wholesale-market designation on every item it makes.
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What an assay establishes
An assay determines the precious-metal content of a sample. In commercial refining, measured composition matters because it helps establish fine-gold content alongside the material’s weight. It also underpins whether a finished bar meets a stated fineness specification.
For refiners on LBMA’s Good Delivery List, assay competence is subject to ongoing scrutiny. LBMA’s proactive monitoring includes supervised samples and independent referee check assays, which compare results rather than relying solely on a refiner’s own stated measurement.
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Source: LBMA’s Proactive Monitoring programme.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What “investment-grade” means—and what it does not
“Investment-grade” is used broadly for bullion products sold as investments; it does not, by itself, identify one universal bar format or certify that a product is acceptable for London wholesale settlement. A retail bar may be a legitimate investment product under the norms of its market without being a London Good Delivery bar.
London Good Delivery is a specific LBMA standard supporting settlement of Loco London wholesale bullion contracts. For gold, its requirements include at least 995.0 parts per thousand fineness, fine-ounce weight within the permitted range, acceptable physical appearance and identifying marks. Qualifying bars are typically around 400 troy ounces and carry a serial number, refiner assay stamp, fineness and year of manufacture. Fineness alone does not make a bar Good Delivery.
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The Good Delivery Lists identify refiners accredited to supply qualifying bars, and listed refiners are subject to ongoing monitoring. LBMA states that other refined products made by an accredited refiner do not thereby become Good Delivery products. In practical terms, the bar itself must meet the relevant specification as well as come from a qualifying refiner. Consult the current LBMA Rules for exact dimensions and tolerances.
Sources: LBMA’s London Good Delivery guide and About Good Delivery.
How to compare gold bullion products
When comparing bars, look beyond a headline purity figure. The relevant details depend on the product’s intended market and the standard it claims to meet.
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Quick Recap
- Fineness: the proportion of the bar that is gold, usually expressed as parts per thousand or a percentage.
- Gross weight and fine-gold weight: gross weight is the whole bar; fine weight is the gold content. These are not interchangeable when the bar is less than pure.
- Format and market: a small retail bar and a roughly 400-troy-ounce wholesale bar are designed for different contexts, even if their stated fineness is similar.
- Identifying marks: check what marks are present and whether they match the claimed standard. London Good Delivery bars have specified identifying marks.
- Refiner and status: a refiner’s accreditation is relevant, but it does not automatically give every product that refiner makes Good Delivery status.
- Chain of custody and applicable norms: consider how the product is authenticated and what market or product standard applies to it; do not assume that one standard covers all retail bars.
Source: LBMA’s London Good Delivery guide.
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