4 Reales - Charles II

Charles II, the last Habsburg king of Spain, ruled under regencies for most of his reign due to severe physical and cognitive disabilities — the result of generations of dynastic inbreeding. The Potosí mint during this period was rocked by the great fraud scandal of 1649, in which assayers had been systematically debasing silver coinage for years; though the scandal predates this issue, the mint's internal controls and assayer accountability remained a contested matter well into Charles's reign.

Cob coinage from Potosí in this period varies considerably in planchet quality, a direct consequence of the hand-hammered macuquina process. The assayer initial on a given piece remains the primary tool for narrowing its date within the 1667–1701 window.