United States
America has no assay office and no government hallmark. A piece carries the maker's own karat stamp — and, by law, the maker's trademark to stand behind it.
In the atlas: NYC Diamond District (47th St) · Los Angeles Jewelry District
Voluntary marking
The National Gold & Silver Stamping Act (1906; trademark amendment 1961) governs marking. There has never been a US assay office — accuracy is enforced after sale by the FTC.
No assay office. Quality marks optional, but a maker's trademark is required if used.
What you'll see struck
Karat stamp
Gold fineness
Karat (10K–24K) or fineness (585, 750). Minimum 10K to be called gold in the US.
Sterling
Silver standard
“STERLING”, “STER” or “925” for 92.5% silver; “coin” silver is 900.
Maker's trademark
Required beside any quality mark
Since 1961, a registered trademark or name must accompany any quality mark, struck at least as large and adjacent to it.
Fineness
- Gold
- 10K (417) · 14K (585) · 18K (750) · 24K (≈999)
- Silver
- Sterling 925 · Coin 900
- Platinum
- 950 Plat · 850/900 Plat · PGM blends disclosed
Hallmark Calculator
See how United States's standards line up with any other country — translate a grade, or compare side by side.
A reference guide, not an authentication service. Marks vary by date and metal; consult the relevant assay office or standards body for definitive identification.