5 Rupees Persian Gulf

The Reserve Bank of India issued a dedicated Gulf series — distinct from domestic Indian notes — specifically for use by Indian workers and merchants operating in the Persian Gulf states, where Indian rupees circulated freely as a de facto currency. Britain's decision to withdraw the Gulf Rupee from the region in 1966, after sterling devaluation pressures made the arrangement untenable, abruptly ended the series. The notes were declared inconvertible for Gulf holders, effectively wiping out savings held in paper form by thousands of migrant laborers.

Pick R2 carries the Gulf designation as an overprint or color distinction to prevent repatriation and arbitrage — a low-tech solution to a currency control problem that was, ultimately, only partially effective.