Hallmark
hall·mark | ˈhȯl-ˌmärk
noun
A mark stamped on jewelry throughout much of the world to attest to the purity of the metal after assay
A hallmark is a mark stamped onto a piece of jewelry that attests to the purity of the metal in the piece after assay. In Europe, hallmarks have been required for hundreds of years and were first implemented in the Middle Ages to protect wealthy buyers from potential fraud. In the United States, there is no law requiring hallmarks on jewelry, but tradition and best practices in the industry mean they are commonly used. A hallmark is designed to indicate the purity of the metal, the country in which it was manufactured, the maker of the piece, and the date it was assayed or registered.