overstamp

An overstamp is a mark or impression applied over another existing mark or impression, typically on a postage stamp or coin. On postage stamps, overstamps are frequently used to indicate a change in the stamp's status or validity. For example, a stamp might be overstamped with the word "SPECIMEN" to denote it as a sample not for sale, or with "CANCELLED" to show it has been used and is no longer valid for postage. Overstamps can also signify a change in currency, a new postal rate, or a commemorative event. Collectors often value overstamped stamps for their historical significance and the stories they tell about a stamp's journey.

In numismatics, overstamping on coins serves a similar purpose. A coin might be overstamped to change its face value, indicate its acceptance in a different territory, or to commemorate a special occasion. For instance, during times of economic change or political upheaval, existing coinage was sometimes overstamped to reflect new monetary values or sovereign authority. These overstamped coins can be of particular interest to collectors studying economic history and the evolution of currency. The process of overstamping requires significant force, and the resulting impression can vary in clarity and design depending on the tools used.