United States
No compulsory hallmarking and — contrary to almost every secondary source — no minimum karat for gold.
| Property | Value | Authority |
|---|---|---|
| Minimum fineness to sell as "gold" | NONE. Unqualified "Gold" requires an article composed throughout of fine (24 karat) gold; any lesser alloy may be sold provided a correct karat designation of at least equal conspicuousness immediately precedes the word "Gold". The Guides set no floor below which gold may not be sold. [1] Widely misreported as a 10-karat minimum. Part 23 DOES set a 10-karat floor in several places — vermeil (§ 23.4) and the plating on gold filled, gold plate and gold electroplate (§ 23.3(c)) — but every one of those governs a COATING over another substrate, not a solid gold article. There is no minimum for solid gold. Conflating the coating rules with solid gold is the likely origin of the myth. Verify against live eCFR before commercial reliance. | § 23.3(b)(1)–(2) |
| Minimum for "sterling silver" | 925/1,000ths pure silver for "Sterling"; 900/1,000ths for "coin silver". [1] | § 23.5(b)(2)–(3) |
| Minimum for unqualified "platinum" | 950 parts per thousand pure platinum for unqualified "Platinum". [1] | § 23.6(b)(3) |
| Hallmarking compulsory | No [1] No independent assay office strikes US articles. Marking is a disclosure duty on the seller, enforced after the fact by the FTC — the opposite of the UK model. | Part 23 generally |
| Assay authority | None. The Federal Trade Commission enforces marking claims under the FTC Act; the National Stamping Act governs marking tolerances. [1] | § 23.5(b), National Stamping Act refs |
| Vienna Convention (CCM) member | No [2] NOT a contracting state. There is no treaty under which a US quality stamp is recognised abroad — and structurally there could not be one, because the US has no independent assay office system for a convention to recognise. Marking there is a seller disclosure duty enforced after the fact by the FTC. | — |
Sources
- 16 CFR Part 23 — Guides for the Jewelry, Precious Metals, and Pewter Industries — U.S. Government Publishing Office (16 CFR Part 23)
- Convention on the Control and Marking of Articles of Precious Metals — Contracting States — Standing Committee of the Hallmarking Convention (Vienna Convention on Hallmarks, Contracting States list)