Each jeweller who submits items for hallmarking must register a maker’s mark (or sponsor's mark) - a shield shape with a minimum of 2 initials inside. Each one is unique and is added to a register of makers that stretches back for centuries. My maker’s mark is registered with the London Assay Office and features my initials, SJS, inside the shield.
In the UK it is a legal requirement for jewellers to have their precious metal work hallmarked if it is over a certain weight. This is 7.78g for silver but I send all my pieces of jewellery for hallmarking, other than small stud earrings, as I believe it not only provides consumer protection but demonstrates to my customers my attention to detail and my commitment to producing high quality pieces of jewellery.
Hallmarking may be considered one of the oldest forms of consumer protection (if not the oldest) as Edward I passed a statute in 1300 trying to prevent frauds being committed by goldsmiths where “Guardians of the craft” assayed work and applied the leopard’s head mark – silver had to be sterling standard (92.5% pure silver which we still use today). In 1363 Edward III established the maker’s mark which was required alongside the leopard’s head and identified the goldsmith responsible for making the item.
Current day testing is high-tech and is now done using non-destructive X-ray Fluorescence Spectroscopy (XRF) technology to sample the items submitted, previously a small sample of the submitted item would have to be removed to be tested.