4 Reales - Carlos III portrait

Carlos III's portrait coinage — the so-called "busto" series — replaced the older milled cob-style pieces across Spanish American mints following a royal decree of 1772, part of a broader Bourbon administrative push to standardize colonial silver. Lima was slower than Mexico City to fully implement the transition, and the overlap period produced considerable variation in die quality as local engravers struggled to match the portrait standards set by the Madrid prototypes.

The KM#77a designation covers a span of four years, during which Carlos III died in December 1788 — meaning some dies were still in use at Lima into early 1789 under his name while his successor Carlos IV was already on the throne in Madrid.