Materials & Hallmarking
The metal and finish are separate parts of a piece’s description. Read the specifications for the coin, setting and chain individually, as they may differ.
Sterling silver
Sterling silver contains 925 parts silver per thousand, with other metals forming the balance. It is often identified by the number 925. A 925 stamp alone is not a full UK hallmark.
Solid gold
Solid gold jewellery uses a gold alloy throughout the stated component, rather than a surface layer. Carat describes its gold content: 9ct is 375 parts per thousand and 18ct is 750 parts per thousand. Check the carat specified on the individual piece.
Gold plating
Gold plating is a layer of gold over another metal. It gives a gold-coloured surface while the underlying metal remains different. The base metal and finish should be read separately; a gold-plated silver piece is not solid gold.
Gold vermeil
The gold vermeil collection uses gold over sterling silver. Refer to each product for the stated gold carat and any further finish specifications. Do not infer the thickness of a gold layer from its colour.
Historic coins
A coin’s metal depends on its issue and date. It may differ from the setting or chain, and some coins have a plated finish. Use the product’s individual material description rather than assuming the whole piece has one composition.
Care for gold-plated jewellery · All jewellery care
Material and fineness
Precious metals are often alloyed with other metals for strength and colour. Fineness states the proportion of precious metal in an alloy. A fineness mark can indicate that standard; by itself, it is not a full UK hallmark.
The UK hallmark
A full UK hallmark has three compulsory marks: the sponsor’s mark, the millesimal fineness mark and the assay office mark. A date letter may also appear, but it is optional. The hallmark is applied by an assay office after testing.
Exemption weights
UK law exempts articles below the applicable weight threshold, subject to the relevant rules:
- Silver: 7.78g
- Gold: 1g
- Palladium: 1g
- Platinum: 0.5g
Other statutory exemptions may apply. A fineness mark alone does not constitute a full UK hallmark.
Hallmarking at Roberts & Co
For items that require hallmarking, Roberts & Co uses The Goldsmiths’ Company Assay Office in London. Each product listing identifies the material and relevant marks with care.