1 Real Phillip IV

The 1622 date places this coin at one of the most catastrophic moments in Potosí's minting history. That year, a royal investigation exposed decades of systematic fraud at the mint — assayers and officials had been debasing silver coinage well below the legal fineness, pocketing the difference. The scandal implicated the highest levels of the mint's administration, and several officials were ultimately executed. Coins struck in the years immediately surrounding the investigation are considered suspect for fineness, though enforcement of the .931 standard improved sharply afterward.

The 8 Real cob of 1622 achieved enduring notoriety through the Atocha shipwreck. Smaller denominations from the same year share that provenance when recovered.