Tibetan silver is used primarily in jewelry components, and is similar to pewter - an alloy of copper, and sometimes tin or nickel, with a small percentage of pure silver. Its overall appearance is of aged silver, but it can be polished to provide highlights on complex castings. Today, the nickel content is reduced or absent, due to common allergies to this metal.
The related term 'Nepalese silver', however, seems to have held on to the higher silver content and association with quality metalsmithing.
Currently, jewelry, beads and castings described as 'Tibetan Silver' tend to be a base iron 'cheese metal' casting, overlaid with this pewter and silver plating. Dependent on source, these can be either thick and robust, or attractive but easily broken due to a loose, fragile inner casting. The latter productions are therefore only suitable for small castings up to around 12 mm, or transient 'fashion' jewelry with a short lifespan.
EBay put on a Buyer's Advisory warning about the possible dangers of Tibetan Silver sold through their site. EBay's Buyer's Advisory