Perth Mint 1 tonne gold coin, 1 tonne Gold Kangaroo coin, measures nearly 80cms wide and more than 12cms deep, weighing a massive 1000 kilograms of 99.99% pure gold. The first 1 tonne gold coin by Perth Mint is certainly the most valuable gold bullion coin in the world with a market price of gold right now, it has a USD$55 million price tag on it. The coin is legal tender in Australia. The coin reverse shows a bounding red kangaroo surrounded by stylized rays of sunlight and bordered by the inscription AUSTRALIAN KANGAROO 1 TONNE 9999 GOLD and the year-date 2012. Read More.