500 Réis - João IV Countermarked 400 Réis

In 1663, Portuguese colonial authorities in Brazil ordered existing 500 réis coins countermarked and revalued downward to 400 réis — a direct response to the chronic shortage of small-denomination silver circulating in the colony and the persistent problem of clipping. The countermark was applied to coins already in circulation, meaning examples show varying degrees of wear beneath the stamp itself.

João IV had died in 1656, so this revaluation was carried out under Afonso VI. The use of João IV's coinage as the host was simply a matter of what was available in circulation at the time.