1 Real - Carlos III

Carlos III's monetary reforms of 1771 mandated the transition from cob ("macuquina") coinage to milled portrait coinage across all American mints, and Potosí was among the last to fully comply. The 1 Real denomination was the workhorse of everyday colonial commerce — broken into halves and quarters by users in the field when smaller change was unavailable.

The Potosí mint sat at over 4,000 meters elevation, and chronic labor shortages at the cerro rico workings during the 1780s created intermittent disruptions to silver supply. KM#52a distinguishes this issue from its predecessor by the assayer initial pairing specific to this window.