1977 $50 Polymer CSIRO Test Note Fine

The development of Australia's polymer banknotes began after counterfeit $10 notes were discovered in 1966. Dr. Herbert "Nugget" Coombs, then Governor of the Reserve Bank of Australia, initiated a project in 1968 involving scientists from CSIRO and universities. Their goal was to create a banknote that couldn't be easily forged, leading to the invention of the optically variable device (OVD). David Solomon led the team that developed the unique polymer substrate and security features. Extensive testing, including durability trials with a "Turbula" machine, ensured the notes' reliability. The first polymer banknotes were issued in 1988, revolutionising currency security worldwide.

This is an incredibly rare and tangible link to the development of modern polymer banknotes.