10K gold (417)

How to read it

Karat marks count pure gold in 24ths: the FTC’s jewelry guides call fine gold 24 karat, and allow a gold alloy to be marked with its karat figure, with or without the word gold (14 Karat, 14Kt., 14 K.). The UK’s Hallmarking Act gives the parts per thousand for each number of carats, 9 being 375 and 14 being 585, “and so in proportion for any other number of carats”; in proportion, 10 works out at about 417. A US 10K mark is the claim of whoever struck it, who under the Stamping Act must also strike their name or trademark beside it.

Also searched as: 10K, 10 karat, 10KT, 417.

Is 10K real gold?

Yes, in the sense the rules use: it is an alloy of gold, and the FTC’s guides allow any gold alloy to be marked with a correct karat figure. It is 10 parts gold in 24, so most of the metal is something else.

The old 10-karat minimum in the US

For decades 10K was the lowest gold that could be called gold in the US. The FTC’s 2018 statement on its revised guides traces the 10-karat minimum to at least 1933, when it appeared in a Commercial Standard issued by the Bureau of Standards; the FTC put it into its trade practice rules for the jewelry industry in 1957. The earlier guides advised against gold terms or quality marks such as 9K on anything under 10 karat. In 2018 the FTC eliminated the 10-karat threshold, so that gold under 10 karat is subject to the same guidance as higher karats: the karat figure has to be disclosed. 10 karat is still the floor in the FTC’s guides for the gold layer of gold filled, rolled gold plate, gold electroplate and vermeil.

How close to 10K the gold has to be

Since 1981 the Stamping Act has allowed the gold to fall short of the marked fineness by no more than three parts per thousand, or seven when the whole article is assayed with its solder (three for a watchcase or flatware). Before then the Act allowed half a carat. The FTC’s guides also list small parts left out of any assay of karat gold, including springs, posts, and bracelet and necklace snap tongues.

The trademark beside the mark

The Stamping Act requires whoever applies a quality mark to apply a trademark, registered or applied for, or their name, by the same means, in lettering at least as large, and as close as possible to the quality mark. The FTC’s consumer guide describes it as the name or trademark of the company that will stand behind the mark, and says it may be a name, a symbol or initials.

10K in Britain

The UK has no 10-carat standard. Its hallmarks strike gold at 375, 585, 750, 916, 990 and 999, and 375 (9 carat) is the lowest. The UK assay offices’ guidance notes say that bonded gold of 10k can only be described as 9 carat in the UK, and that a manufacturer’s fineness mark on a piece of jewellery counts as a description, which brings the piece under the hallmarking law.

Karat or carat?

The Hallmarking Act spells it carat and reads so many carats as a claim about gold, except where the word is used as a measure of weight for precious stones. That is the carat on a diamond report, a unit of weight with nothing to do with gold purity. The FTC’s guides count both spellings, karat and carat, as quality marks.

Where the mark should be

The FTC’s guides say a stamped or engraved quality mark should be large enough to be legible to persons of normal vision and placed where purchasers are likely to see it.