Instructions
Look at the denomination, which is the face value. It should be expressed in dollars or cents. This will establish whether the coin is likely to be American. The denominations created by the 1792 Act were the half cent, cent, half disme or half dime (5 cents,) disme (ten cents,) quarter dollar, half-dollar, dollar, quarter eagle ($2.50,) half-eagle ($5) and eagle ($10.) The half cent and cent were made of copper, the three kinds of eagle of gold and the remainder were silver. Coins varied in size. The act required the disme to be one tenth the size and weight of a dollar. Early coins were struck at either the Philadelphia or San Francisco mints, indicated by a P or S mintmark.
Check the coin for a impressed year of issue, which should be on the obverse or head, directly under the design. This will be the most self-evident indication of an old American coin. If the year is worn or obscured, you will need to do additional research.
Examine the coin's designs. Before the twentieth century, American coinage restricted itself to depicting symbols, such as the eagle and Lady Liberty, either as a full figure covered in drapery or as an idealized bust. From the early 1900s, coins diversified to depict American presidents, such as Abraham Lincoln on the penny, and other images, such as the Indian head, and buffalo nickels. The absence of such designs can indicate a pre-1900 American coin.