Jim,,if its not turning your finger blackish it has a high degree of silver in it.
Depending on what they alloy in now could be any combo of Tin, Copper, Brass, and God knows what else if it was 835 or even 900 you finger would turn color...
As far as tarnish,,if you wear it most the time, wash your hands with it on etc. it will never tarnish while on you.
You are absolutely right Gaspare. Anything with silver less than .900 and sometimes even .900 will turn color on your finger depending on alloy.
If ring is in active use it will not tarnish on finger. It will start tarnish only if it is not in use for some time.
And silver hardness depends on alloy used to make it, like copper, zinc or anything else that are used to change silver properties. .925 silver is sterling silver no matter what alloy is used, coper, zinc, palladium etc. As far there is 92.5% silver. For example in silver coins and silverware usually are nickel additives to make them wear resistant. Al is used to eliminate casting porosity, Zn to make better flow of liquid silver etc.
