50 Dollars - Elizabeth II 4th Portrait - Platypus - Gold Bullion Coin

Australia's gold bullion platypus series was introduced by the Perth Mint in 2002 as a direct competitor to the long-established Kangaroo/Nugget series, targeting collectors who wanted an annually changing design within a consistent wildlife theme. The .9999 fineness — four nines — was a deliberate commercial decision to exceed the .9990 standard then common among rival sovereign mint bullion products, most notably the Canadian Maple Leaf, which only achieved four-nines purity that same decade.

The 2010 issue coincides with Ian Rank-Broadley's fourth portrait of Elizabeth II, adopted by Australian coinage from 1999 onward.