40 Réis - João Prince Regent Countermarked 20 Réis

In 1809, the Portuguese crown — then operating from Rio de Janeiro following the Napoleonic invasion of the Iberian Peninsula — faced an acute shortage of circulating copper. Rather than strike entirely new coinage, the remedy was pragmatic: existing 20 Réis pieces were counterstamped and revalued to 40 Réis, effectively doubling their face value overnight. The operation allowed the exiled court to expand the money supply without the infrastructure a full mint retooling would have required.

Counterstamp quality varies considerably across surviving examples, a predictable consequence of applying dies to coins already in circulation.