Sheffield Assay Office is one of only four offices in the country that tests (assays) and hallmarks precious metals. The office also operates a UKAS accredited Analytical Services Laboratory that offers a range of additional analytical services from metal and mineral analysis, to mercury screening and environmental testing, as well as an accredited Diamond Verification Service. Sheffield Assay Office was the first UK Assay Office to be awarded UKAS accreditation and is proud to have retained that accreditation for more than 30 years.