100 Dollars - Elizabeth II 4th Portrait - Kangaroo - Gold Bullion Coin

The Perth Mint's Australian Kangaroo bullion series has carried a rotating reverse design since 1989, a deliberate policy distinguishing it from competitors like the Krugerrand and Maple Leaf, which lock in a fixed design year after year. The strategy was partly commercial — annual design changes drive collector demand on top of pure bullion interest — but it also complicates registry sets and makes date-matching for complete runs genuinely difficult.

The .9999 fineness adopted for this series was, at its introduction, finer than virtually any major sovereign bullion program then in production.