In order to work silver, which is soft, a harder alloy, usually copper, has to be added. This makes the quality of silver very variable depending on the percentage of copper.
Sterling silver is most widely known and used in Great Britain, Ireland and the US. It consists of 925 parts silver per 1000, a grading dating from Henry VIII’s time. This is known as “Britannia Silver”.
Silverplate, EPNS or Electroplated Nickel Silver looks like silver but has only a thin covering of silver on nickel base or sometimes copper. This process was patented by G.R. Elkington in 1840, a few months before a similar process was patented in France by Roulz.
Apart from Elkington, the chief manufacturers of EPNS are Reed and Barton in the US and Elkington’s licensee in France, Christofle. Old Sheffield Plate, sometimes confused with EPNS, named after the town in which it was invented, is a process of plating by fusion. This was invented in the mid-18th century by Thomas Boulsover and then industrialised by Matthew Boulton and other entrepreneurs of the period. The base metal of old Sheffield Plate is copper alloyed with a small amount of zinc onto which silver is fused. This is then pressed into sheets from which objects are wrought.
Thus, a piece of Sheffield Plate is easy to identify and considered very collectible unlike its EPNS descendant.