500 Ekueles Corisco island

Corisco is a small island off the coast of Equatorial Guinea with a history far more tangled than its size suggests — it was formally ceded to Spain in 1843 under treaty with local Benga chiefs, and remained a minor administrative footnote through the colonial period. The island gives its name to this issue, part of Equatorial Guinea's recurring practice of producing large-format bimetallic pieces aimed squarely at the collector market rather than circulation, a revenue strategy the country has pursued aggressively since the 1990s.