Britannia standard
noun
A standard for silver in which the fineness is set at.958 (i.e. 95.8 per cent silver).
- Introduced in England by Act of Parliament in 1697 to replace sterling silver (92.5 per cent) as the obligatory standard for items of silver plate; the sterling standard was reinstated in 1720..
Origin
Late 19th century; earliest use found in The Times.