Starting 2018 the Perth Mint has released 2 coins in Next Generation Mother and Baby series featuring Koala and Crocodile. These are piedfort coins, which means that they are thicker than usual ones. Coin Dimensions: Thickness: 6.42 mm Diameter: 40.6 mm Mintage - 75,000 Lowest price for 2 oz 2018 Mother & Baby Next Generation Australia Koala $2 Silver Bullion Coin .9999 is $1.50 at Provident Metals. Lowest price for 2 oz 2019 Mother & Baby Next Generation ...