Fineness Stamp

The fineness stamp – also called a punch mark or hallmark – is the most important marking on bars, coins and jewellery made of precious metal. It indicates the proportion of the total weight that is pure metal, and thus forms the basis for every melt value as well as for the legal classification as VAT-exempt investment gold.

Where does the mark come from?

The stamping of silver and gold articles goes back to the Middle Ages. From 1300, English goldsmiths had to bring their work for testing to Goldsmiths' Hall in London – hence the term hallmark. In the German-speaking world, the guild authorities developed their own punch marks, which often indicated not only the fineness but also the master and the place of testing.

Today the Vienna Hallmarking Convention (International Convention on the Control and Marking of Articles of Precious Metals, 1972) governs a uniform Common Control Mark for its member states, including Austria, Switzerland and a number of other European countries. In the UK, hallmarking is compulsory under the Hallmarking Act 1973 and administered by the four Assay Offices (London, Birmingham, Sheffield, Edinburgh).

How is fineness indicated?

The stamp follows a parts-per-thousand scale (‰). Alongside it, the older carat notation for gold still exists in the jewellery sector:

For silver, common stamps are 999, 925 (sterling silver), 835 and 800; for platinum, 950 and 999 dominate.

What else appears on the mark?

A complete hallmark impression typically contains several elements:

1. Fineness figure – e.g. "750" for 18-carat gold
2. Maker's mark – abbreviation or logo of the refinery or manufacturer
3. Assay office mark / guarantee stamp – for officially tested articles, a state symbol (e.g. the leopard's head for London)
4. Date letter or mint mark – for coins, the so-called mint mark
5. Serial number – on certified bars, often laser-engraved

For LBMA Good Delivery bars (400-ounce gold bars) the bar's individual serial number is additionally required.

Significance when buying and selling

When buying from a dealer or refinery, the fineness stamp is the first thing to be checked. If it is missing or appears to have been tampered with, the achievable purchase price drops considerably – in case of doubt the dealer will require an independent analysis (streak test, X-ray fluorescence). With the current gold price and the stamped fineness, the material value can be calculated to the second.

For the VAT exemption of investment gold in the UK (HMRC), a minimum fineness of 995 ‰ (gold) is required, in line with Directive 2006/112/EC. Coins and bars without this evidence cannot be traded as VAT-exempt investment gold. Investment gold is VAT-exempt, whereas silver, platinum and palladium attract 20% VAT.

Note: Tax and legal classification of individual products should be clarified with a qualified adviser in case of doubt – this text does not constitute tax or investment advice.

Authenticity testing beyond the stamp

The stamp alone is not proof of authenticity. Professional testers always combine it with further methods:

• Weight and dimension check (Coin Weight Checker, Coin Size Checker)
• Density method according to Archimedes
• X-ray fluorescence analysis (XRF) – non-destructive, highly precise
• Ultrasound – exposes tungsten inserts in bars
• Online authenticity check – quick orientation via reference data

In brief

The fineness stamp is the legally anchored core document of every precious-metal item: it names the purity, enables the calculation of the material value and determines the tax classification. Anyone buying, selling or inheriting bars or jewellery should know the stamp and, in case of doubt, have it confirmed by an independent analysis.