There has been some report's of fake silver coins delivered from seller's on eBay. Here is a quick and easy way to make sure before staking from one source .

You don't want to be that guy who stakes silver in one large box only to find out years later, it is all fake.
Acid test.. reliable but dangerous to have it around the house so be careful.

He explains it clearly as clear as the Sun in the sky

Strong magnet..not 100% accurate but it will do for some coins.

Next is gold ..