In the early 1980s, the United States Mint began planting the Philadelphia Mint mintmark on coins. In 1982, this was still a relatively new practice, and the mint was manually punching these mintmarks onto the working dies. Despite the labor-intensive nature of the process, error still prevailed. The mint made two errors during this time. Here are two examples of these errors. First, off center strike. A dime struck off center has an image that is not properly aligned or struck. In addition, a coin struck between two dies may also be a mule.
A second type of error occurs on the reverse of a dime. This type of error results when the die used to strike the coin fails to strike the clad. A missing layer in the nickel clad exposes the copper core. A 1999 dime with this defect can fetch as much as $30. Unlike its normal counterpart, a 1999 dime with a clipped planchet is a high-value coin.