15 Dollars - Elizabeth II 4th Portrait - Discover Australia - Goanna - Gold Proof

The Discover Australia series ran from 2006 through the early 2010s, with the Perth Mint issuing these small-format gold proofs to target the international bullion gift market rather than domestic circulation. The goanna entry appeared relatively late in the series, by which point the program had expanded well beyond its original dozen animal subjects.

At 3.135 grams of .9999 fine gold, the fractional weight was deliberately calibrated to a $15 AUD face value — a denomination with no circulating equivalent, existing purely as a legal-tender device for these collector issues.