Reference

A glossary of gold.

The gold trade runs on a vocabulary that is precise, old and rarely explained. These are the 30 terms that recur most often in our reporting — what each one actually measures, and why it matters to anyone reading a price, a bar stamp or a mining company's accounts.

Markets

Troy ouncealso: ozt: The unit gold is priced and traded in, equal to 31.1034768 grams — about 10 percent heavier than the avoirdupois ounce used for groceries. A quoted gold price of $2,400 an ounce always means a troy ounce. The unit descends from the medieval fairs at Troyes in Champagne and survived into modern bullion markets because contracts, refinery bars and assay certificates were all written in it.
London Bullion Market Association (LBMA): The trade body that sets the standards the wholesale gold market runs on. Its Good Delivery List names the refiners whose bars are accepted without re-assay in London vaults, and its Responsible Sourcing programme audits where their metal comes from. The LBMA does not itself trade gold or set the price; it defines the specifications, accreditation and reporting that make anonymous bars fungible between counterparties.
LBMA Gold Pricealso: London fix, gold fix: The twice-daily benchmark, set at 10:30 and 15:00 London time through an electronic auction operated by ICE Benchmark Administration. Participants submit buy and sell volumes at a proposed price; the price moves until the imbalance falls within tolerance and the auction settles. Because it produces a single printable number for a fixed moment, it is what miners, refiners, ETFs and central banks write into contracts.
Good Delivery bar: The wholesale unit of the London market: a bar of roughly 400 troy ounces (about 12.4 kg) at minimum 995 fineness, carrying the stamp of an accredited refiner, a serial number, the year of manufacture and the assayed fineness. Weight is variable rather than fixed, so bars are traded on their actual fine gold content. A bar that leaves the vault chain of custody must be re-assayed before it is accepted back.
Allocated vs unallocated gold: Allocated gold means specific, serial-numbered bars held in your name; the vault is a custodian and the metal is not on its balance sheet, so it survives the custodian's insolvency. Unallocated gold is a claim on a bullion bank for a quantity of fine gold, not on identified bars — cheaper and more liquid, but an unsecured credit exposure. Most wholesale trading clears unallocated; most long-term reserve holding is allocated.
Contango and backwardation: Contango is the normal state of the gold futures curve, where forward prices exceed spot by roughly the cost of financing and storing metal. Backwardation, where forward prices sit below spot, signals that someone will pay a premium for metal now — usually a squeeze on physical availability rather than a view on the price. In gold, sustained backwardation is rare and treated as a stress indicator.
Gold lease rate: The interest paid to borrow physical gold, historically derived as the difference between dollar interest rates and the gold forward offered rate. Central banks and ETFs lend metal; refiners, miners and jewellery fabricators borrow it to cover the gap between buying feedstock and selling finished product. A spike in lease rates means physical metal has become scarce in a specific location, not that the gold price is rising.
Central bank reserve gold: Gold held by a monetary authority as a foreign reserve asset. It carries no counterparty and no currency of issue, which is why it is bought most heavily by central banks seeking to reduce exposure to any single sovereign. Holdings are reported monthly to the IMF, usually valued at market price, and are often stored abroad — a large share of the world's reserve gold sits in New York, London and Basel rather than at home.

Assay & purity

Fineness: Gold purity expressed in parts per thousand. 999.9 fineness — 'four nines' — is 99.99 percent gold, the standard for investment bars and coins. 995 is the London Good Delivery minimum. Fineness is the wholesale market's language because it is a direct mass fraction, unlike karat, which expresses the same idea in twenty-fourths and is used in jewellery.
Karatalso: carat, kt: A twenty-fourths scale for gold content in an alloy: 24k is pure gold, 18k is 750 parts per thousand, 14k is 583, 9k is 375. Karat measures only how much gold is present, not which metals make up the rest — and the balance determines colour, hardness and tarnish behaviour. Pure gold is too soft for most settings, which is why almost all worn jewellery is alloyed.
Fire assayalso: cupellation: The reference method for determining gold content, unchanged in principle for centuries. A weighed sample is fused with lead and fluxes, then heated in a porous cupel where the lead oxidises and is absorbed, leaving a bead of precious metal. The bead is parted in acid to remove silver and the remaining gold is weighed. It is slow and destructive, but it remains the arbiter when a result is disputed.
XRF analysis: X-ray fluorescence, the fast non-destructive check used at pawn counters, scrap desks and customs benches. The instrument excites the sample and reads the characteristic emission of each element present. Its weakness is depth: XRF reads only the surface, so it can be defeated by heavy gold plating over a tungsten or base-metal core. Serious verification pairs it with density, ultrasound or a drilled sample.
Hallmark: A set of marks struck by an independent assay office certifying that an article's gold content has been tested and meets the declared standard. A full hallmark typically records the sponsor, the fineness, the assay office and a date letter. In jurisdictions with compulsory hallmarking it is a legal guarantee rather than a maker's claim, which is why hallmarked antique pieces can be dated and attributed so precisely.

Mining

Ore grade: How much gold a tonne of rock contains, quoted in grams per tonne. Large open-pit operations can be economic at around 1 g/t; underground mines generally need several grams to justify the cost of getting to the rock. Grade drives everything downstream — at 1 g/t a mine must move a tonne of material to produce roughly a third of a gram of sellable metal, which is why energy and haulage dominate the cost base.
All-in sustaining cost (AISC): The industry's standard measure of what it costs to produce an ounce and keep producing it: mining and processing costs plus royalties, site administration, sustaining capital and reclamation accruals, divided by ounces sold. It deliberately excludes expansion capital and exploration for new deposits, so a company can report a healthy AISC while quietly depleting its reserve base — read it alongside reserve life, never alone.
Cut-off grade: The lowest grade of material worth processing rather than dumping as waste. It is a function of the gold price, recovery rate and processing cost, so it moves as those move: a higher gold price lowers the cut-off, converting waste into ore and enlarging the reserve without any new drilling. This is why reserve statements change with the price and must always be read with their assumed gold price attached.
Reserves vs resources: A resource is gold known to be in the ground with reasonable geological confidence. A reserve is the part of a resource that a study has shown can be extracted profitably under current costs, prices, permits and technology. Every reserve is a resource; most resources never become reserves. Reporting codes such as JORC and NI 43-101 exist precisely to stop the two being blurred in investor material.
Artisanal and small-scale mining (ASM): Labour-intensive gold mining by individuals and small groups, typically with minimal mechanisation and often outside formal permitting. It produces a material share of world supply and supports millions of livelihoods, but it also accounts for the largest anthropogenic release of mercury on earth, used to amalgamate gold from concentrate. Formalisation and mercury-free processing are the central policy questions in the sector.

Refining & recovery

Doré: The impure alloy a mine pours on site, typically somewhere between 60 and 90 percent gold with silver and base metals making up the rest. Doré bars are not tradable bullion; they are feedstock, shipped under insurance to an accredited refiner where they are assayed and settled on contained fine gold. The step from doré to Good Delivery bar is where the mining industry ends and the bullion market begins.
Miller process: Chlorine refining. Chlorine gas is bubbled through molten doré; base metals and silver form chlorides that rise as a slag and are skimmed off, leaving gold at roughly 99.5 percent purity in a matter of hours. It is fast and cheap, which is why it is the first stage in most refineries, but it cannot reach investment-grade purity on its own — that requires electrolysis afterwards.
Wohlwill process: Electrolytic refining that takes gold to 999.9 fineness. Impure gold anodes are dissolved in a chloroauric acid electrolyte and pure gold plates onto the cathode while impurities either dissolve or drop out as anode slime, from which platinum-group metals are recovered. It ties up a substantial gold inventory in the cells and takes days rather than hours, so refiners run it only for the purity grades that need it.
Cyanide leachingalso: heap leach, CIL: The dominant method of extracting gold from ore. A dilute cyanide solution dissolves gold into a complex that is then recovered onto activated carbon or by zinc precipitation. Heap leaching stacks crushed ore on a lined pad and irrigates it; carbon-in-leach agitates finely ground ore in tanks. The chemistry is efficient and well understood; the risk sits in solution containment and in the tailings that remain afterwards.
Tailings: The ground rock and process water left after the gold has been extracted, stored behind engineered embankments. Because ore grades are low, tailings dwarf the product by orders of magnitude, and their long-term stability is the largest environmental liability a mine carries. Failures are rare but catastrophic, which is why dam design, water balance and closure bonding now sit at the centre of mine permitting.
Urban miningalso: e-waste recovery: Recovering gold from discarded electronics rather than ore. A tonne of circuit boards can carry a hundred times the gold of a tonne of typical ore, concentrated in connectors, bonding wire and plating. The constraint is not chemistry but logistics and safety: collecting, sorting and de-soldering mixed waste without releasing brominated flame retardants or heavy metals is what determines whether recovery is economic.
Recycled goldalso: scrap gold: Gold returned to the refining stream from jewellery, industrial residues and investment bars, supplying roughly a quarter to a third of annual demand. Supply is strongly price-elastic: when the price rallies, scrap flows to the counters within weeks, which makes recycling a natural brake on price spikes. Once refined, recycled gold is chemically identical to newly mined metal and cannot be distinguished by assay.

Craft

White gold: A gold alloy whitened with palladium, nickel or silver, then almost always plated with rhodium for a bright neutral finish. The underlying alloy is generally faintly warm rather than truly white, so the visible colour of a worn ring is often the plating rather than the metal. Rhodium wears off over years of contact, which is why re-plating is routine maintenance rather than a repair.
Rose gold: Gold alloyed with a high proportion of copper, which supplies both the pink colour and a notable increase in hardness. The depth of colour tracks the copper fraction, so 18k rose is subtler than 14k rose at the same nominal karat family. Higher-copper alloys can develop a surface patina over time and are less forgiving under the torch, which affects how a piece is sized and repaired.
Vermeil: Sterling silver plated with a defined minimum thickness of gold — typically 2.5 microns at 10k or finer under US rules. It is a regulated term, not a marketing one, which distinguishes it from ordinary gold plating where the layer may be a fraction of a micron. The distinction matters in wear: a thin flash plate can rub through in months, while true vermeil survives years of regular use.
Lost-wax castingalso: investment casting: The oldest method still used to make gold jewellery. A wax model is encased in a refractory investment, the wax is burned out, and molten gold is drawn into the resulting cavity by vacuum or centrifuge. Almost every mass-produced ring passes through it. Its limits set the vocabulary of design: wall thickness, sprue placement and shrinkage all constrain what a caster will accept from a drawing.
Gold filled: A mechanically bonded layer of karat gold making up at least 1/20 of an article's total weight, pressure-bonded to a base-metal core rather than deposited electrically. It is orders of magnitude thicker than plating and can last decades in normal wear. It is not solid gold and has little refining value, but it is the reason well-made early twentieth-century costume pieces still look intact today.

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