Australia has two mints, the Royal Australian Mint (which also makes the country's circulating coinage) and the Perth Mint, which are both very active in the bullion coinage space; coins issued by them are legal tender.
Additionally, there are private issuers of bullion which is not legal tender and is targeted at investors and not at coin collectors - such as this one.
The Mint says about this product:
More than a billion years ago, rare miracles of nature were formed in secrecy deep beneath the Earth’s surface. Discovered below the ancient boab trees in the heart of the Kimberley in Western Australia’s far north are the rarest diamonds in the world.
A selection of seven precious Argyle Pink Diamonds have been superbly hand set into a 1oz 22 carat pink gold bullion ingot, crafted by The Perth Mint. Embodying a pink theme throughout, copper has been added to traditional yellow gold to create a beautiful pink gold finish. Polished to perfection, this exclusive investment piece depicts a native boab tree with six Argyle pink diamonds embedded into the design. | 
Search for Australia: Gold Ounce (2015) Argyle Pink Diamond, Pink Gold Ingot on eBay 