“Coin” or “coin silver” stamped on a spoon, a cup or a piece of jewellery is a statement of fineness, the same as a number would be. In the United States it has a fixed meaning: the silver is at least 900 parts per thousand pure, or 90%. That puts it below sterling, which is 925. This page sets out where that definition comes from, how strictly it is held, and how the 900 standard is treated in the UK and India, using the rules themselves. It puts no value on any piece.
The US definition
Two US instruments define coin silver, and they agree. The FTC’s Jewelry Guides, at 16 CFR § 23.5(b)(3), say that using the word “coin” or “coin silver” to describe all or part of an industry product is misleading unless it is at least 900/1,000ths pure silver. The National Gold and Silver Stamping Act, at 15 U.S.C. § 296, attaches the same figure to the stamp: an article may be marked “coin” or “coin silver” only if its silver parts contain 900 parts per thousand pure silver.
So “coin”, “coin silver” and “900” all point at the same standard in the US. The word is a name for a fineness, the same way “sterling” is the name for 925.
Coin silver and sterling side by side
The difference is 25 parts per thousand. A 100 g piece of silver that truly meets the coin standard holds at least 90 g of pure silver; a sterling piece of the same weight holds at least 92.5 g. The remaining metal is other metals, which neither definition names. The two standards sit next to each other in the same section of the Jewelry Guides, which treat “Sterling”, “Sterling Silver”, “Solid silver” and “Ster.” as misleading below 925 and “coin” as misleading below 900.
One more line in § 23.5 matters for old pieces. Note 1 to the section points out that the National Stamping Act bars silver-plated articles from being stamped “sterling” or “coin”. So in US law the word “coin” on a piece claims solid silver at that fineness, not a plated surface. The silver plated vs sterling guide covers plate.
How far short a coin mark may fall
Section 296 allows a small divergence. A silver part tested with no solder may fall short of the coin standard by no more than four parts per thousand, so 896 is the floor. The whole article, solder included and assayed as one piece, may fall short by no more than ten parts per thousand, so 890. The Act says both tests apply together. The silver stamp tolerance calculator works these figures out for “coin”, “sterling” and any numbered silver mark, from the same constants this page quotes.
As with all US silver marks, there is no test before sale. Nothing obliges a maker to stamp silver at all, and no government office checks the stamp first. The mark is the maker’s or seller’s claim, and the law fixes what the claim must mean.
In the United Kingdom
900 is not one of the UK’s standards. Schedule 2 of the Hallmarking Act 1973 lists four silver standards, 800, 925, 958.4 and 999, so a UK hallmark never shows 900 as its fineness mark. The word “coin” has no defined meaning in the UK Act, so a US coin-silver stamp is not a UK hallmark, and the usual UK rules apply to describing the piece as silver in trade. The guide to UK hallmarking covers those rules.
In India: listed in 2014, dropped in 2025
India’s silver hallmarking standard is IS 2112. Its 2014 edition listed six purity grades, 800, 835, 900, 925, 970 and 990, so 900 was a valid Indian hallmark grade. A Press Information Bureau release of 4 September 2025 says the 2025 edition replaced it with seven grades, 800, 835, 925, 958, 970, 990 and 999. 900 is not among them. Silver hallmarked in India at 900 is therefore from the older scheme, and silver hallmarked from September 2025 will not show it. The India silver hallmark grades tool compares the two lists.
What a coin stamp does not tell you
- That the piece was made from coins. In US law the word names a fineness. This page makes no claim about how any piece was made, and the rules quoted here do not either.
- Who made it, or when. A bare “coin” identifies no maker and no date.
- That it is genuine. A word can be struck on anything. The fake hallmark guide covers the signs that a mark does not fit the piece.
- What it is worth. The silver content gives a melt value, which the silver value calculator works out at 900 or any other fineness. What an object fetches is a different number, and this site keeps the two apart.
Sources
- 16 CFR § 23.5, FTC Guides for the Jewelry, Precious Metals, and Pewter Industries (Cornell LII), read 20 October 2026, including Note 1.
- 15 U.S.C. § 296, National Gold and Silver Stamping Act (govinfo.gov).
- Hallmarking Act 1973, Schedule 2 (legislation.gov.uk).
- Press Information Bureau, Ministry of Consumer Affairs, release 2163768 (4 September 2025), on IS 2112:2025 and IS 2112:2014.