Historically 'Tibetan Silver' did contain pure Silver, and some old items may be predominantly Silver. Zangyin is a Chinese term for 'Tibetan silver' - it seems to originate from a scholar's term for the inferior silver adulterated with high proportion of copper used for Tibetan coinage in the late Qing Dynasty period.
In modern usage refers to a variety of white non-precious metal alloys used primarily in jewellery components, with an appearance similar to aged silver. 'Tibetan Silver' includes copper-tin alloys; zinc alloys; and other alloy compositions, as well as base metals such as iron plated with a Sterling Silver alloy. An X-ray analysis showed that six of seven items acquired online and described as 'Tibetan silver' were alloys containing primarily copper, zinc.
Sometimes comparable metallurgical compositions have been called Nepalese silver, white metal, lead-free pewter, base metal or simply tin alloy.
Tibetan Silver can occasionally contain Nickel or Lead (usually found in old Pewter), which can be a problem with people with sensitivities or toxicity worries. I will always ensure to the best of my ability that my Tibetan Silver is Lead and Nickel free by buying from reliable sources.
Tibetan Silver is generally used for charms and beads or anything that is cast, it is not suitable to make wire or anything thin gauged, therefore is not used for ear-wires and chains due to it lack of tensile strength.
Tibetan Silver can tarnish like any other metal be-it Sterling Silver, base metals or plated alloys. As a general rule don't get it wet, if you do, dry and polish with a soft cloth. If it goes dull or tarnished, a gentle polish with a non-abrasive Silver cloth will bring it's lustre back.