500 Dollars - Elizabeth II 3rd Portrait - Koala - Platinum

Australia's platinum Koala series launched in 1987, positioning the Perth Mint directly against the Canadian Maple Leaf and American Eagle in the nascent investor-grade platinum market. The one-ounce $500 denomination was the flagship of the range, and the 1991–92 issues are notable for carrying Ian Rank-Broadley's predecessor — Raphael Maklouf's third portrait of Elizabeth II — in its final years before the fourth effigy superseded it across Australian coinage in 1999.

Mintages for individual dates in this series were tightly controlled and never disclosed in full at time of issue, a deliberate Perth Mint policy intended to sustain collector premiums above spot.