Quite honestly the best way to protect your self with any purchase is with a simple $20 pocket scale. Buy a Redbook as all weights are listed for every U.S. coin made at the beginning of each series. Counterfeiters are great at getting the the designs copied but terrible at getting the weights correct. And of course there are now testers available to measure gold and silver content but that is out of the price range and budget of most collectors and I am fortunate enough, after retiring, to go to work in a coin shop! Guess I worked all my life to finally find some heaven! lol