20 Pesos

Colombia's Banco de la República introduced this denomination during a decade when the country's monetary system was under sustained pressure from inflation — the peso lost roughly two-thirds of its purchasing power between 1982 and 1989. The 20-peso coin's aluminium bronze alloy was chosen partly for its resistance to corrosion in tropical circulation conditions, a practical concern the Colombian mint had learned from earlier copper-nickel issues that degraded quickly in humid lowland regions.

Heavy use across nearly a decade means circulated survivors dominate. Uncirculated examples from the early years of the run are the ones worth seeking out.