The Britannia is a British bullion gold coin issued since 1987, which contains one troy ounce of gold and with a face value of £100. There are also fractional Britannia coins, weighing a half, quarter, and one-tenth of an ounce, with face values of 50, 25, and 10 pounds respectively. The coins have a millesimal fineness of 917 (91.7 %, 22 carat) gold, the non-gold component being copper until 1989 and silver from 1990.
In 1997 the Royal Mint started production of silver bullion coins also under the name "Britannia". The alloy used is Britannia silver with millesimal fineness 958 (95.8 %). The silver coins are available in 1 ounce, 1/2 ounce, 1/4 ounce, and 1/10 ounce.
Silver Britannias have been released each year beginning in 1997, when a silver proof set was offered. In 1997 and in all subsequent even-numbered years the reverse design has depicted a standing Britannia figure. Beginning in 1999 and continuing in odd-numbered years, a series of alternate, non-repeating depictions of Britannia have replaced the standing figure on the reverse.