from Tokyo in 2016. Japanese hallmarking is optional. Gold, silver and platinum are subject to assay. The articles combined with the golden parts and the platinum parts are hallmarked with special marks. See also Hallmark Silver hallmarks References External links The Goldsmiths' Company London Assay Office Swiss federal customs administration (Fr.) Vienna Hallmarking Convention Signatories’ Assay Offices Irish Assay Office website Assay Office Birmingham International Association of Assay Offices (IAAO) ("Copyright") 2017, retrieved 2019-10-29 - list of members plus Palestine as observer, including numerous seals Analytical chemistry Coins Watches Jewellery Product-testing organizations