10 Réis - Maria I Countermarked 5 Réis

Portugal applied countermarks to existing colonial copper as a cost-saving measure rather than striking entirely new coin. This piece began life as a 5 Réis and was officially revalued to 10 Réis by countermark — a practice the Crown leaned on repeatedly when copper shortages or fiscal pressures made a full reminting impractical. Maria I's reign saw considerable monetary disorder in Brazil, partly driven by the difficulty of supplying adequate small change to a colony of that geographic scale.

The countermark itself is the authentication event. Pieces that avoided the official stamp continued to circulate at the old value, creating a two-tier system in practice if not in law.