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

Australia's gold koala bullion series has shifted reverse designs almost annually since its 1980 launch — a deliberate policy by the Perth Mint to prevent secondary-market hoarding and encourage annual collector turnover. The 2013 issue falls within the Ian Rank-Broadley obverse portrait period, the fourth effigy of Elizabeth II used on Australian coinage, introduced in 1999.

The .9999 fineness specification places this above the more common .9990 standard, a distinction Perth has maintained on its bullion program since the 1990s as a direct competitive response to the Canadian Maple Leaf.