British sterling silver (925 purity)
British sterling silver was named after the coinage of the realm, being 92.5% pure (hence 925) and has been assayed or hallmarked (i.e. tested for purity in the assay halls) since around the year 1300.
In 1544 the lion passant mark often referred to as the 'sterling lion', was introduced and remains today the hallmarking symbol of British sterling silver.
Charms and small items of silver may display various marks or none at all.
All items of silver which weigh over 7.78 grams must be hallmarked according to British law. This hallmark is impressed on the piece at one of the British assay offices... today only London, Birmingham, Sheffield and Edinburgh. All British hallmarks must include the following separate marks: The maker's or sponsor's mark; fineness, purity or control mark (eg 925 for sterling silver); assay or town mark (eg the anchor for Birmingham). Other marks eg. the lion passant and date letter are now optional.
Most small silver items will not have a full hallmark but may be marked 'sterling', 'silver' or 'silv' / 'sil' for short. They may also be marked 925.
You can be confident that you are buying a sterling silver item, which is produced in the UK, as long as you purchase from a legitimate supplier who will vouch for the purity of the metals used. This guarantee chain is rigorously enforced down the line to the Bullion source or smelters.
Check to see if your supplier is a member of either the British Jeweller's Association (BJA) or the National Association of Goldsmiths (NAG). These are the two trade bodies who support and help regulate the British Jewellery industry.