The Platinum Koala is the most famous series of Australian platinum coins. On 18 June 1987, the Australian Government approved the minting of platinum and silver coins, and accepted them as legal tender. This decision was made based on the success of gold coins issued a year earlier. The minting of the "Platinum Koala" began in September 1988 in Perth. For marketing purposes, 2 ounce, 10 ounce, and 1 kilogram coins of silver, gold and platinum were introduced in 1991; the 1 kg coins were the world's heaviest bullion coins at the time.