Wis. Stat. § 134.27: Misbranding of coin silver articles.

(1) Except as provided in sub. (2) and s. 134.29, any person who sells any article of merchandise made in whole or in part of silver or of any alloy of silver marked with the words “coin” or “coin silver”, or any colorable imitation of “coin” or “coin silver”, unless nine hundred one-thousandths of the component parts of the metal appearing or purporting to be silver are pure silver is guilty of a misdemeanor.

(2) In the case of all articles that are subject to sub. (1), there shall be allowed a divergence in fineness of four one-thousandths parts from the standards under sub. (1).