counterstamp

A counterstamp is a mark or stamp applied to a coin or other piece of currency after it has already been minted. These marks can be applied by various authorities, individuals, or groups for a range of purposes. Historically, counterstamps were often used to indicate that a coin had been officially recognized and accepted for use in a particular jurisdiction, especially when coins from different mints or regions circulated together. They could also denote a change in the coin's value or a new legal tender status.

In some cases, counterstamps were applied by private merchants to guarantee the weight or purity of a coin, acting as a form of endorsement. During times of conflict or economic instability, counterstamps were sometimes used to devalue or revalue coinage, or to signify that a coin was still valid despite its origin from an enemy territory. The practice continued into the modern era, with governments occasionally counterstamping foreign coins to adapt them for domestic circulation. Collectors value counterstamped coins as they represent a unique historical record of a coin's journey and the economic or political events it experienced.