Gold Britannia Introduced by the Royal Mint in 1987, the Gold Britannia coins are British gold bullion coins that have begun to play a major role on the coin market. Gold Britannia are issued in 1oz sizes with face values in British pounds (£) of £100, Gold Britannia are 917 gold (22-karat gold) and are legal tender in Great Britain. Until 1990, the Gold Britannia was alloyed with copper. However, beginning in 1990, the Gold Britannia has been alloyed with silver, which gives the Gold Britannia issued since 1990 a lighter yellow color than the earlier Britannia. In 2013, the fineness increased to .9999 fine.