The excerpt below, from Lydia Darbyshire’s book, Antique Silver: The New Compact Guide and Identifier, provides information on the silver standard and registration marks.
“The silver content of 17th and 18th century pieces varied widely. If they were made from melted coins, the content depended on the country of origin. After the War of Independence, the mint fixed a lower standard of 892 parts per 1,000 for US; this was raised to 900 parts per 1,000 in 1837 and, finally, in 1869 sterling standard came into common use and goods were stamped “sterling”. From the mid-1800s until 1869 it was customary to stamp goods with an indication of quality such as “standard”, “C” or “coin”, “quality” or “premium”.
OLD SHEFFIELD PLATE
One of the most successful ways of covering objects made of a base metal with a silver coat or “skin” was discovered c.1743 by Thomas Boulsover (or Bolsover, 1704-88) of Sheffield. He accidentally found that if a thin layer of silver were fused to an ingot of copper, the two metals could be rolled as one, each expanding at the same rate under pressure. Sheets of silver fused to copper could be produced in this way and then cut up to make objects. At first only one side of the copper was plated, but by the mid- 1760s both sides of the ingot were silver-plated.
Boulsover made small pieces, snuff boxes and livery buttons, for example — but other Sheffield and Birmingham metalworkers quickly exploited the process, and they made a wide variety of objects, including such large pieces as tureens and trays. Much old Sheffield plate is unmarked and can be dated only by comparison with hallmarked silver.
In the 1850s registration marks were introduced in Britain to record the exact date of manufacture of items of electroplate. Registration marks are not hallmarks.”