A quality mark is never anonymous
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The requirement
A person applying a quality mark indicating gold or silver content must also apply a trademark "which has been duly registered or applied for registration under the laws of the United States within thirty days after an article bearing the trademark is placed in commerce or imported into the United States, or the name of such person".
Two acceptable options
A registered trademark, or applied-for within thirty days, or the name of the person. For a sole maker the name is the straightforward answer.
Why the Act works this way
A fineness claim is only checkable if somebody is accountable for it. An anonymous 14K stamp is an assertion nobody can be held to, and the trademark is what makes it attributable.
Which is the same logic as a tracking label
The resin jewelry property covers the children's product marking requirement, where a permanent mark exists so a cohort can be identified. Different statute, same instinct: a claim needs an author.
The thirty days run from commerce, not from filing
An article bearing the trademark placed in commerce starts the clock. That makes the registration part of launching a line rather than something to catch up on.
Multi-part articles
Parts marked with quality indications matching in pattern and size, in lettering at least as large as the quality mark itself. A chain and its clasp have to agree.
Which is a real bench problem
Findings are bought in rather than made, and a 14K chain finished with a gold-filled clasp is two different claims on one object.
Lettering at least as large
Which prevents the obvious evasion of a prominent quality mark and a microscopic qualifier. The same instinct appears in the hair care property, where a warning may not be set smaller than what it warns about.
The stamp is physically difficult on small work
Which is a real constraint and not an excuse. A piece too small to carry both marks is a piece that should carry neither.
And that is a legitimate choice
No quality mark, no trademark requirement. Sold described accurately, it is lawful, and for a lot of handmade work it is the sensible route.