Dealer Notice and Hallmarking
What is hallmarking?
A hallmark tells you who made the item known as a sponsor's mark (i.e. my sponsor's mark is my initials S.IDE), what metal the item is, where it was hallmarked and what year the piece was hallmarked in. See an explanation from London Assay Office here.
It’s a legal requirement for silver over 7.78g, gold and palladium over 1g, and platinum over 0.5g to have a UK recognised hallmark. Items that are under this weight do not necessarily need to be hallmarked.