How to Know That My US Gold Eagle Is Real?

Weigh the coin on a set of sensitive jeweler's style scales. A 1-oz. Gold Eagle will in fact weigh in at 1.0909 troy ounces, because it contains exactly 1 oz. of pure gold and a small amount of toughening alloy. Similarly, the 1/2-oz. coin actually weighs 0.5455 oz., the 1/4-oz. coin 0.2727 oz. and the 1/10-oz. coin 0.1091 oz. Any base metal forgery will probably be much lighter.

Check the diameter of the coin with a pair of calipers. The diameters for the different sizes of Gold Eagle are 1.287 inches, 1.063 inches, 0.866 inches and 0.650 inches.

Consider the coin's finish. Although the bullion and proof coins bear the same designs, the finish is different. The proof coins receive multiple strikes to give the raised parts a frosted luster over a mirrored background. The bullion coins won't have this level of attractiveness, but will still be crisply detailed. Fakes will not be able to match this quality, and in particular fake proof coins will be especially obvious as they will not bear the appropriate frosted luster.

Learn the coin's provenance -- that is, its history. The ways in which proof and bullion coins are sold differs slightly. Proof coins are available directly from the U.S. Mint, while you can only buy bullion coins through an authorized broker. For absolute certainty, you should buy your Gold Eagles in this manner yourself. But if buying them from another investor or collector, expect to see receipts of the original purchase and accompanying documentation from the U.S. Mint. The proof coins in particular should come in presentation packs. With fakes the provenance will be absent or incomplete.