I do not know if this had been posted before, but this website has a very clear and definitive video on how to spot counterfeit American silver eagles, I had a bunch of eagles (monster boxes) at one time and sold them to buy a gold coin.
http://www.newcoinreleases.com/aler...lver-eagles/my apologies if this has been shown before, but if not, it is a very easy to follow guide... there are a lot of ads and such, but if you can ignore the ads and just view the video it may be very helpful on spotting individual fakes.