Precious Metals

The process of testing precious metals to ensure their quality		Assay
Certifies the quality of precious metals (in Britain)		Assay Office
Hall in the City of London where all precious metals were (originally) officially inspected and marked, giving its name to the hallmarking process		Goldsmiths' Hall
Hallmarked since 1974 (in the UK)		Platinum
Hallmarked since 2009 (in the UK)		Palladium
The four hallmarks of English silver		Town mark
		Maker's mark
		Date letter
		Sterling letter
Smooth, fine–grained but abrasive stone used for testing precious metals – name used metaphorically for any method of testing the validity or merit of a concept		Touchstone

Assay mark for Birmingham			Anchor
Assay mark for Edinburgh			Castle (Barbican)
Assay mark for London			Leopard's head
Assay mark for Sheffield (since 1977)			Rose
Assay mark for Sheffield (up to 1977)			Crown

A seated female figure (Hibernia) is the assay mark of; sterling silver, and gold of 22 carats or above, are hallmarked with a crowned harp

Carats in pure gold		24
Carat rating of gold bearing the number 375		9 (37.5% pure)