1 Dollar - Elizabeth II 4th Portrait - Treasures of Australia - Diamonds

The "Treasures of Australia" series, launched by the Royal Australian Mint in the mid-2000s, was designed around the country's four principal natural resources — gold, diamonds, sapphires, and opals. The diamond issue draws directly on the Argyle mine in Western Australia's Kimberley region, which by 2009 was producing over 90% of the world's pink diamonds and roughly a third of all natural diamonds globally by volume.

Argyle's output was extraordinary in quantity but complicated in quality — most stones were industrial grade. The mine closed permanently in 2020, a decision that has since driven pink diamond prices to record levels.