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

Australia's platinum Koala series launched in 1987, making Perth one of the earliest sovereign mints to issue a platinum bullion program in fractional denominations. The 1/10 oz piece anchored the lower end of that range, targeting collectors who wanted platinum exposure without committing to the one-ounce format. Perth's .9995 purity standard edged out the more common .9990 fineness used by most competitors at the time — a deliberate marketing distinction during a period when platinum briefly traded above gold.