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.