jewellery luxury precious-metals standards Hallmarks¶ The standard mark¶ Describes the fineness of the material, which is purity measured in parts per 1000. Purity Gold Silver 375 X 585 X 750 X 800 X 916 X 925 X 958 X 990 X 999 X X References¶ https://en.wikipedia.org/wiki/Hallmark