50 Cents - Elizabeth II 4th Portrait - Federation - Colourised Proof

Issued to mark the centenary of Australian Federation, this piece belongs to a six-coin colourised series released by the Royal Australian Mint in 2001 — each coin depicting one of the six states at the moment of their unification on 1 January 1901. The pad-printing technique applied to circulating-format copper-nickel was still a relative novelty for the RAM at this point, and the process drew some collector criticism for inconsistent colour adhesion on early production pieces.