The largest gold coin weighs 100 kg (220 lb 7 oz), measures 50 cm (19.6 in) in diameter, 3 cm (1.1 in) in thickness and is made from bullion with a purity of 99.999 per cent. The legal-tender coin was introduced on 3 May 2007 by the Royal Canadian Mint with a face value of CAN$1 million (US$900,375; £451,585).