Altered stamps is an activity that teaches the young stamp collector to identify hidden details, differences in stamp designs and printing flaws that may occur during the stamp production process. The printing plates used during the production process can become worn through use. Sometimes the plates are reengraved or reproduced. This can result in minor differences between the different printings of the stamp. These small changes sometimes have a significant impact on the value of a stamp.

Here are a number of practice examples of stamps that have been altered. The stamp on the left is the original, the stamp on the right is the altered stamp. If you scroll down on the PDF document the answer key will appear. There are 10 differences on each pair of stamps. Can you identify all of the changes?

More altered images will be added in the upcoming weeks.