countermark

A countermark is an auxiliary mark impressed onto an existing coin after its original minting. Usually applied by an authority other than the mint that produced the coin, the countermark can take the form of letters, numerals, monograms, or symbols. It is typically struck with a punch and may overlap the coin’s design or appear as a separate impression.

The purpose of countermarks varies. They can revalue a coin, authenticate it for acceptance in a new jurisdiction, certify payment of a tax, or indicate the authority that overruled or redistributed the currency. Countermarks may also signal debasement adjustments, reallotte coins for local use, or identify coins that have been repurposed from one monetary system to another.

Countermarks have been used across many cultures and periods, from ancient Greek and Roman coinage through medieval and early modern Europe and beyond. They are common on coins that circulated over wide geographic areas or underwent political changes, where local authorities needed to assert control or compatibility of foreign coinage with domestic standards.

In numismatics, countermarks are of interest because they illuminate monetary history, circulation networks, and political authority. They can complicate authentication and valuation since a single coin type may bear multiple countermarks, each reflecting a different time, place, or purpose.

See also: counterstamp, overstrike, overprint.