What a UK hallmark actually is
A hallmark is an official stamp applied to precious metal to confirm what it is made of. In the UK, hallmarking has a long history and is governed by law: items made of gold, silver, platinum or palladium above certain weights must be independently tested and marked before they can legally be described and sold as that metal. The marking is carried out by an Assay Office, not by the manufacturer, which is why a genuine hallmark is a reliable, independent guarantee of the metal's purity.
For anyone curious about a piece of jewellery at home, the hallmark is the single most useful thing to look at. It tells you the type of metal, how pure it is, and often where and when it was tested. None of that tells you what an item is worth on its own, but it is the starting point for understanding what you actually have.
The fineness numbers: 375, 585, 750, 916
Modern UK hallmarks show purity as a three-digit fineness number. This is the amount of pure gold in the metal, expressed in parts per thousand. The common gold finenesses are:
- 375 – 9 carat gold (37.5% pure). The most common gold used in everyday UK jewellery.
- 585 – 14 carat gold (58.5% pure). More common in imported and some modern pieces.
- 750 – 18 carat gold (75% pure). Often used in higher-quality rings and fine jewellery.
- 916 – 22 carat gold (91.6% pure). Frequently seen in traditional and South Asian jewellery.
- 990 / 999 – Very high purity, close to pure gold, more common in bullion than wearable jewellery.
You may also see older pieces marked simply "9ct", "18ct" and so on, or with a crown symbol that was historically used alongside the carat mark for gold. Higher fineness means more pure gold by proportion, but it does not automatically mean a piece is more valuable overall, because weight and the amount of metal present both matter too.
The assay office mark
UK hallmarks include a symbol showing which Assay Office tested the item. There are four operating today, each with its own emblem:
- London – a leopard's head
- Birmingham – an anchor
- Sheffield – a rose (historically a crown for some metals)
- Edinburgh – a castle
If you spot one of these tiny symbols, it confirms the piece was tested by a recognised UK office. Older items may carry the marks of offices that have since closed, such as Chester or Glasgow, which can be of interest to collectors.
The date letter
Many hallmarks include a date letter – a single letter in a particular font and shield shape that indicates the year the item was assayed. The style of the letter and its surrounding shape change each year, so specialists can often pinpoint when a piece was tested. Since 1999 the date letter has been optional, so its absence on a newer item is perfectly normal. Where it is present, it can be helpful for dating antique and vintage jewellery.
Alongside these, a full traditional hallmark may also include a sponsor's (maker's) mark showing who submitted the item, and sometimes a standard mark symbol for the metal type.
How to find the marks on your jewellery
Hallmarks are deliberately small and discreet, so it helps to know where to look:
- Rings – inside the band.
- Necklaces and bracelets – on the clasp, or on a small flat tag near it.
- Earrings – on the post or fitting.
- Watches and lockets – on the case back or inside the casing.
A magnifying glass or jeweller's loupe, plus good light, makes a real difference. Marks can be faint, worn smooth with age, or hidden by years of polishing. If you find yourself squinting at a worn band, don't worry – that is completely normal, and a faint mark does not mean there is anything wrong with the piece.
What to do if an item appears unmarked
An item with no visible hallmark is not necessarily fake or worthless. There are several innocent explanations:
- The piece may be below the weight threshold that legally requires hallmarking.
- It may be older or foreign and made before or outside UK hallmarking rules.
- The mark may simply be worn away or hidden.
Equally, an unmarked item may not be solid gold, or could be plated. The honest answer is that you usually cannot tell purity from appearance alone. A professional can carry out non-destructive testing, such as electronic or acid testing, to establish what the metal actually is. Be cautious of any item described as gold with no marks and no testing, particularly when buying.
Turning marks into an informed decision
Reading a hallmark is genuinely useful, but it is only part of the picture. The value of any gold item depends on its weight, its fineness, the live gold price on the day, and whether it has additional worth as a designer or antique piece. Anyone offering to buy gold should be happy to explain how they weigh and test it, and to show you their reasoning.
This guide is general information, not financial advice. If you would like to know exactly what your pieces are, you are welcome to bring them to a reputable buyer in your area for a free, no-obligation valuation whenever it suits you.