100 Rupiah

The 1959 Indonesian 100 Rupiah was issued during a period of acute monetary instability — the government launched a currency reform that same year, slashing the face value of high-denomination notes by half and requiring registration of holdings above a set threshold. The measure was aimed squarely at suppressing inflation and undermining black market cash hoards accumulated during the Sukarno-era spending boom.

Thomas De La Rue's involvement here is routine for the period; Indonesia relied heavily on foreign printers through the late 1950s before developing domestic capacity. The watermark is the sole mechanical security feature, which made competent counterfeiting a persistent concern.