Britannia Silver Coins (.958)
Britannia Silver was introduced in 1697 in Britain following William III's recoinage a year earlier. It was used for silver sheet metal work instead of Sterling Silver but in 1720 the country reverted back to the stronger alloy.
The Royal Mint revived Britannia Silver usage for their Silver Britannia coins in 1997. This lasted until 2012, and since 2013 the Mint has made pure .999 silver coins.