1 Sol de Oro

Peru's transition to brass for this denomination was a wartime necessity — the copper-nickel alloy used in earlier issues became strategically restricted as Allied industrial demand consumed base metal supplies through the early 1940s. The Banco Central de Reserva made the switch in 1943 and simply never reversed it, running the same brass composition through two decades of political upheaval including the Odría coup of 1948.

The 22-year production span under a single KM number masks meaningful die and mintage variation across issues, particularly between Lima Mint output in the late 1950s and the final strikes approaching decimalization in 1965.