8 Reales - Charles III

These years at Potosí fall squarely within the aftermath of the 1765 mint scandal, in which assayer Domingo de Santiesteban was found to have systematically debased the silver coinage for years — reducing fineness well below the legal standard while pocketing the difference. The resulting royal investigation and assayer purge forced a complete reorganization of the Casa de Moneda's quality controls, and coins struck in this narrow window carry the transition assayers' marks that document the cleanup effort in real time.

Potosí's milled coinage of this period was produced on screw presses introduced under Bourbon reform pressure, replacing the old macuquina tradition the mint had relied on for over two centuries.