Items may be exempt from hallmarking due to weighing less than:
1 gram for Gold
7.78 grams for Silver
0.5 grams for Platinum
1 gram for Palladium
Items may be exempt due to having been tested and hallmarked in a country signed up to the International Convention on Hallmarking and bears the convention Common Control Mark. Items may also be exempt if it bears other European hallmarks considered to be of the equivalent guarantee to consumers, these must contain a sponsors/makers mark, fineness mark and an assay office mark.
Items stamped with just the numbers 925 and similar are not hallmarked.
The assay office will test the item of jewellery for it's precious metal content before hallmarking. There are 3 compulsary marks that an assay office will apply:
Sponsors Mark
This is a unique mark of the individual or company who sends the item to the assay office. The sponsor could be anyone from the maker to the retailer.
Standard Mark
This mark is to show the purity or fineness of the metal.
Assay Office Mark
This mark denotes which Assay Office tested and marked the item.
Birmingham - Anchor
Edinburgh - Castle
London - Leopard's head
Sheffield - Yorkshire Rose
Metal Fineness or Purity
Carat measurements indicate the content or fineness of gold in the metal alloy.
9ct Gold – 37.5% pure gold (375)
14ct Gold – 58.5% pure gold (585)
18ct Gold – 75% pure gold (750)
22ct Gold – 91.6% pure gold (916)
Other recognised finenesses of gold in the U.K. are 99% (990) and 99.9% (999)
10ct is not a recognised value in U.K. hallmarks.
Silver Content
Sterling Silver - minimum silver content of 92.5% (925)
Britannia Silver – minimum silver content of 95.8% (958)
Fine Silver - minimum silver content of 99.9% Silver (999)
Other recognised finenesses of silver in the U.K. are 80% (800)
