4 Reales - Philip IV

This piece dates to 1652, the year of the infamous "fraud of Potosí" — one of the largest monetary scandals in Spanish colonial history. For years, mint master Francisco Gómez de la Rocha had been systematically debasing the silver content of cobs struck at Potosí, producing coins well below the mandated fineness. When the fraud was finally exposed, the Spanish crown recalled and demonetized enormous quantities of macuquerina coinage across the Americas and Europe, triggering a financial crisis that stretched from Lima to Seville.

Gómez de la Rocha was executed. Coins struck in the years immediately surrounding 1652 exist in a documentary gray zone — assayer attribution on surviving pieces from this period remains a persistent complication for specialists.