Fineness, mintage, proof, assay, key date, Good Delivery — if you're new to precious metals collecting, here's a plain-English reference for the terms you'll run into constantly.
Short answer: this is a reference, not a single-concept guide — bookmark it and come back whenever you hit an unfamiliar term in another article or a dealer listing. Below are the terms that come up constantly across bullion buying and coin collecting, defined plainly.
Fineness — the purity of a precious metal, expressed as a decimal out of 1.000 (e.g., .9999 fine = 99.99% pure). See our full purity guide for the common tiers.
Troy ounce — the standard weight unit for precious metals, equal to about 31.1 grams — slightly heavier than a standard (avoirdupois) ounce used for most other goods.
Karat — an alternative way of expressing gold purity out of 24 parts (24-karat = pure gold, 22-karat = 91.67% gold).
Spot price — the current live market price for immediate delivery of a given metal, updated continuously during trading hours.
Premium — the amount a coin or bar sells for above spot price, covering minting costs, dealer margin, and (for collectible pieces) scarcity value.
Buy/sell spread — the difference between what a dealer pays you to buy your metal and what they charge to sell it — their margin, not a sign of a bad deal by itself.
Bullion strike — the standard, non-proof version of a coin, produced for investment rather than collector presentation.
Proof — a specially struck coin with a mirror-like finish, produced using polished dies and often multiple strikes for extra detail — typically a collector product, not a plain bullion piece.
MS / PF grades — Mint State (for bullion/uncirculated strikes) and Proof grades on the standard 1-70 numeric scale third-party graders use.
Raw — a coin that hasn't been professionally graded and encapsulated, as opposed to a "slabbed" graded coin.
Key date — a specific year (or year/mintmark combination) within a series known for unusually low mintage or historical significance, commanding a premium over common dates.
Mintage — the total number of coins produced in a given year or release — the primary driver of a date's relative scarcity.
Finite series — a coin program designed from the outset with a fixed, planned number of releases, as opposed to an open-ended annual program. See our finite series guide.
LBMA Good Delivery — the accreditation standard determining which refiners' bars trade freely on wholesale markets without further assay. Full explainer here.
Assay — the process of testing a metal's purity and composition, either by a refiner certifying a new bar or a buyer verifying a questionable one.
Melter/assayer mark — a refiner-specific hallmark stamped on a Good Delivery bar identifying who produced and certified it.
This list isn't exhaustive, but it covers the terms you'll encounter most often across dealer listings, grading services, and the rest of this site's guides. When in doubt about a term you haven't seen defined, it's almost always worth looking up before a purchase rather than assuming.
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