1 Dollar - Elizabeth II 4th Portrait - Koala - Silver Proof Coin

The Australian Koala silver bullion series launched in 2007 and deliberately rotates its reverse design annually — a policy the Perth Mint adopted specifically to drive collector demand and discourage melting, distinguishing it from static-design bullion programs like the Kangaroo series. The fourth portrait of Elizabeth II, by Ian Rank-Broadley, was itself introduced on Australian coinage in 1999 and remained current until replaced by the Jody Clark effigy in 2019.

Struck to .999 fineness rather than the .9999 of some competing sovereign mint issues — a distinction worth noting for buyers assembling matched sets.