does silver rust?

If you look carefully at these coins, most of them are made of 99.9% silver, and you may also notice that some of them are shiny, and some have some kind of black-ish stuff on them.
Silver won't 'rust' but they do tarnish, which in a practical point of view, is basically the same thing. But in reality it isn't.
Chemically, silver is made of the element...well...silver (Ag) But the tarnished silver is (Ag2S) (2 atoms of silver, and one of Sulfur) when rust iron oxide (Iron with oxygen in varying amounts.)

So Silver won't rust, but it will tarnish at the touch if touched too much, but according to theory, it can be removed with Hydrochloric acid.

To answer the specific question, silver won't tarnish in water unless it contains ozone (O3) or Hydrogen sulfate (H2S), but same goes for air.

As far as white ginto goes, white ginto is just ginto mixed with silver, and ginto doesn't tarnish, so I would say the chain is pretty safe.

Hope this helps.

Go google it. But I think either it does rust or it Tarnishes. Whateva that means :D