The Australian one ounce silver piece (abbreviated as 1 oz and designated with Ag for "silver") is a bullion coin format. Uniquely, in Australia there are two mints independently authorised to strike legal tender: the Royal Australian Mint (which also makes the country's circulating coinage) and the Perth Mint which only makes collector and bullion coins, as well as other bullion products.
The Australian Koala series by the Perth Mint comes in several sizes and compositions: 1 kg silver, 5 oz silver, 1 oz silver numismatic (proof, high relief) and 1 oz silver bullion. The Royal Australian Mint also issues silver Kookaburra bullion coins.
The reverse design changes every year, always featuring a koala - one of the most famous and distinctive animals native to Australia. The silver ounce coins have a face value of 1 dollar, but this is only symbolic - as the bullion value of their precious metal content is much higher. The coins were .999 fine silver until the 2018 edition, which increased in purity to .9999 silver. The overall weight is slightly more than an ounce, so that the pure silver content is exactly 1.000 ASW (troy ounce Absolute Silver Weight).
This coin is part of the Australian Koala series by the Perth Mint. It is not only high relief but also the first koala coin which is incused.
The Mint says about it:
Traditionally motifs on a coin have raised relief. However, where the design is described as incused, it is pressed into the surface of the blank. This rarely seen technique has been used to remarkable effect on the reverse of this special addition to our Australian Koala family of collectables.
The Australian Koala is a sought-after coin series featuring annual designs of the much-loved marsupial. Sleepy and docile, koalas spend most of their time either resting or eating gum leaves among Australia’s eucalyptus forests.
The coin’s reverse portrays an incused impression of a cute koala on a tree branch - the first Australian Koala release to be struck in this way. The coin’s obverse features a traditional high relief strike of Her Majesty The Queen. | 
Search for Australia: Silver Ounce 2020 Australian Koala, High Relief on eBay 
