Difficult to tell unless we knew what the coins in question were.
Most silver coins are however genuine, mainly due to their low value ( Many don't make much above scrap weight ), so little point in faking them, unlike gold coins.
There are of course obvious exceptions, such as rare coins, high grade ones, significant dates, etc.
Also "Sound Tests" are rarely correct, size is however a good guide, as is weight, but on that point if they are very old coins can be a little out ( As in lighter ) due to wear over the years.
I suspose it really depends on how much you paid & if you purcased them as say for example an investment, but agai that only really applies to rarer coins.
If you have one near you try popping into a local coin dealer outlet or even a pawnbrokers ( Not a high street chain ) the little independant ones are the best, they usually have a vast knowledge of these sort of things & will probably be able to help you.
