Things You'll Need
Instructions
Search through the coin's packaging for a certificate of authenticity. While it is possible that this certificate can be counterfeited, it is much more likely that the coin is real if it has one of these certificates. Set aside any other identifying papers as well.
Take notes of all of the identifying features of the coin it has no paperwork. Note the country of origin, date, engravings on both the front and the back, and any other features that may help you define your coin.
Look through an up-to-date coin guide for $50 or commemorative (since no $50 coins were ever minted for circulation) coins. A good guide will have pictures that you can compare to your coin. If the coin does not exist in the guide, it is likely not an authentic government-issued coin. You should also use your notes to make sure that the exact type of coin you have is listed in the guide as well.
Take the coin to a coin store if you are still unsure of the authenticity of your coin. The dealers there should be able to tell you all you need to know about your coin's authenticity.