Ag; atomic number 47 on the Periodic Table of Elements. Next to gold, it is the most malleable and ductile element. Silver is stable in pure air and water but will tarnish if exposed to ozone, hydrogen sulphide, or sulphur.
Fine silver. Pure unalloyed silver; hallmark stamped as "FS" or "FS.999".
Sterling silver. An alloy containing 92.5% (or more) silver and other metals, typically copper. Hallmarked "925" or ".925". Tarnishes more rapidly than fine silver.
Argentium sterling silver. An alloy containing 93% silver with copper plus germanium. The germanium reacts to form germanium oxide on the surface, lending this alloy a greater resistance to tarnish than traditional sterling silver. It is hallmarked as sterling silver.