1 Rupiah

Indonesia's aluminium small denominations of this period were struck as the country clawed back economic stability following the catastrophic hyperinflation of the Sukarno years, when prices had risen over 600% annually by 1965. The transition to Suharto's New Order government brought a sweeping monetary reform program — the rupiah was redenominated in 1965 at 1000:1 before these coins ever entered production.

Aluminium was chosen specifically to keep intrinsic metal value well below face value, a lesson learned painfully from earlier issues that disappeared from circulation the moment their composition became worth more than their denomination.