UK hallmarking rules do not stop you describing jewellery; they stop you describing it as platinum, gold, palladium or silver, in whole or in part, unless it is hallmarked or exempt. The offence is built on description. So the metal claims on a product page, including any AI-written ones, are what the law looks at.
That makes AI copy a real risk, not a theoretical one. A language model writing "solid gold look chain" or "sterling silver style bracelet" has no idea which words cross the line, and it will happily produce the sentence a regulator would query. The answer is to turn the rules into a short banned-claims list that sits in every prompt and in your sign-off check. The guidance quoted below is the Assay Offices' hallmarking guidance notes, a November 2022 edition that was still the one GOV.UK listed in November 2026; check for a newer version and ask an Assay Office or your local trading standards service when in doubt. This is general information, not legal advice.
The rule in plain words
The guidance explains that nobody can tell by sight or touch how much platinum, gold, palladium or silver an item contains, so the law requires a hallmark on items described as made of those metals, subject to exemptions. The main offence, as the notes state, is that a person in the course of trade or business must not:
- describe an unhallmarked article as wholly or partly made of platinum, gold, palladium or silver, or
- supply, or offer to supply, an unhallmarked article to which such a description is applied.
Three points in the guidance matter to anyone writing product pages.
- A description can be written, spoken or a stamp. The notes say a description can be verbal, written, or in the form of a manufacturer's fineness marks on a piece of jewellery. Your product title, bullet points, image captions, alt text, meta description and social posts all count as written description.
- Online selling is covered. The guidance says the requirement applies to anyone in the course of trade or business with UK consumers, and applies equally to e-commerce, distance selling, gallery shops, market stalls and physical retail premises.
- New and pre-owned items are both covered. Resale of second-hand jewellery does not escape the rule, although some exemptions apply.
One more duty sits beside the description rule, and AI page builders never add it for you. GOV.UK's guidance for businesses says every dealer supplying precious metal items must display the Dealer's Notice, in the form produced by the British Hallmarking Council, and that online retail sites must prominently display explanatory information about the hallmark, using Dealers Notice A or Dealers Notice B (a PDF or short film for online platforms). The notices are free from the Assay Offices. If your shop template has no hallmarking page or notice, add one before you worry about the wording of any single listing.
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Buy nowThe thresholds that decide what needs a hallmark
Items below a set weight are exempt. The weights in the notes are:
| Metal | Exemption weight (below this, no hallmark required) | Minimum legal fineness (parts per thousand) |
|---|---|---|
| Platinum | 0.5 grams | 850 |
| Gold | 1.0 gram | 375 |
| Palladium | 1.0 gram | 500 |
| Silver | 7.78 grams | 800 |
Three details change how you apply that table. For an article made of precious metal and base metal together, the weight is the total metal weight including the base metal, so a small silver charm on a heavy chain may still be over the line. Where an item contains more than one precious metal, the minimum weight of the most precious one applies. And a pre-1950 item can be described and sold as precious metal without a hallmark if the seller can prove it is of the minimum fineness and was made before 1950.
The guidance also lists other exempt articles on its pages 16 to 18, which are not reproduced here. Read that list for anything unusual, such as items for particular uses, and do not assume your item is exempt because it looks like one on a forum.
Why a stamp is itself a claim
A "925" stamp or a gold fineness mark on an item is a description of its metal. An underweight silver piece may carry a 925 stamp, but an item that does not meet the fineness it states, or that is stamped with a fineness it cannot support, is a problem on its own. Photographs that show a stamp should match the words around them. If your listing says "silver plated" and the image shows a "925" stamp, one of the two is wrong.
Plated items: the wording the guidance sets
This is the area where AI copy goes wrong most often, because plating terms sound similar and models treat them as interchangeable. The notes are specific.
Gold plated silver
- Gold plated silver articles are hallmarked as silver.
- If the word gold or a gold fineness is used, the article must be described as silver and the word gold must be directly followed by plated. The example given is "18ct gold plated silver ring".
- Other terms such as vermeil may be used in addition, but "gold plated" and the word "silver" must still appear, for example "18ct gold plated vermeil silver ring".
- Silver gilt may describe a gold plated silver article, provided no gold fineness is applied in the description.
- The plated layer must be at least 375 parts per thousand gold and the guidance says it should not exceed 2 microns in thickness.
- Examples of misleading descriptions that are not allowed include "22ct gold clad ring" and "22ct gold vermeil ring".
Gold plated base metal
- Gold plated base metal items cannot be hallmarked. That covers bonded gold, rolled gold and plated gold on base metal.
- The terms bonded gold, rolled gold and gold plated are allowed to refer to plated silver or plated base metal items.
- For bonded gold, the layer must be at least 375 fineness and of a fineness recognised in the UK, so bonded gold of 10 karat can only be described as 9 carat there.
Colour words on base metal pieces
The notes address words such as gold or silver used as a colour. If the article contains no precious metal or falls below the minimum fineness, and the word is used as an adjective for colour, the description must make that clear. Their example is blunt: calling a base-metal watch with no gold a "gold watch" to describe its colour would be an offence. They suggest wording such as "yellow metal", "gold tone" or "gold coloured", offered as examples and not as a complete list.
Turning the rules into a banned-claims list
A rule written for lawyers does not help a language model. A list of phrases it must not produce, with allowed replacements, does. This table is a starting point; adapt it to the metals you actually sell and check each line with an Assay Office or trading standards service.
| AI might write | Why it is a problem | Safer wording (if the facts support it) |
|---|---|---|
| "Gold necklace" for a gold plated brass piece | Describes an unhallmarked item as gold | "Gold plated brass necklace" or "gold tone necklace" |
| "Sterling silver look" or "silver style" on a base metal piece | Implies the metal without saying it is not | "Silver tone", "silver coloured", or the real base metal named |
| "22ct gold vermeil ring" | The guidance lists it as misleading | "22ct gold plated vermeil silver ring" only if the layer and fineness are true |
| "Gold clad" or "gold filled" without checking | Not in the permitted list of plating terms I could see; unverified claims | Use "gold plated", "rolled gold" or "bonded gold" only as defined, or leave out |
| "Solid gold" on a hollow or plated item | States a purity and construction that is false | Remove, and state the real construction |
| "18ct" or "925" on a piece with no marking or test | A fineness is a precise claim that needs evidence | Quote only what the hallmark or the maker's tested specification shows |
| "Hallmarked" on an item without a hallmark | False statement about a legal mark | Say "hallmarked" only for items carrying a full hallmark |
| "Sterling silver" on an item with silver plating only | Mixes plating with solid metal | "Silver plated" and name the base metal |
| "Platinum finish" on a rhodium or base metal item | Implies platinum content | "Rhodium plated" if true, or describe the colour |
| "Genuine gold" or "real silver" with no mark or weight | Vague purity claim, no hallmark | Remove or replace with the hallmarked fineness |
The prompt block to paste into every jewellery prompt
Put the rules in the instructions, not in the hope that the model remembers them. Keep the block in one saved place, such as a ChatGPT Project or Claude Project instruction, so every listing starts with it.
You write product pages for a UK jewellery shop. Follow these rules exactly.
METAL FACTS: Use only the metal, fineness, plating and weight in the PRODUCT FACTS
block. Never infer them from the product name, the price or a photo.
NEVER write: gold, silver, platinum or palladium (or "sterling", "solid", "genuine",
"real", "pure", "karat/ct" figures, or "925/750/375" numbers) unless PRODUCT FACTS says
the item is hallmarked or says it is exempt and gives the tested fineness.
PLATED ITEMS: Write "gold plated silver" (word "plated" directly after "gold") only if
the base is silver. For base metal, write "gold plated [named base metal]" or "gold tone".
Never write "gold vermeil" or "gold clad" with a carat figure. Never drop the word
"plated".
COLOUR WORDS: If the item has no precious metal, describe colour as "gold tone",
"silver tone", "gold coloured" or "yellow metal". Never "gold" or "silver" alone.
If PRODUCT FACTS is missing anything you need, write "[CHECK: ...]" instead of guessing.
Add a final line: "Metal claims used:" listing each one so a person can check it.
PRODUCT FACTS:
[paste]The last two instructions do the real work. A "[CHECK]" placeholder stops guessing, and the closing "Metal claims used" list gives your reviewer one line to compare against the hallmark and the supplier's specification.
A worked example: auditing twelve listings
An illustration with invented products. A small online shop sells twelve pieces of jewellery and has used a chatbot to write all the descriptions. The owner copies every metal phrase into a sheet and checks it against the facts she holds from suppliers.
| Listing | AI wrote | Facts held | Verdict |
|---|---|---|---|
| Hoop earrings | "Gold hoops" | Gold plated brass, 3 g pair | Fix: "gold plated brass hoops" |
| Signet ring | "Solid silver signet ring" | Hallmarked silver, 14 g | OK, hallmark image included |
| Charm bracelet | "Sterling silver charm bracelet" | Silver chain 6 g, brass charms | Fix: describe the chain and the charms separately; total weight is what matters for the exemption |
| Pendant | "18ct gold vermeil pendant" | Gold plated silver, layer thickness unknown | Fix: "gold plated silver pendant"; remove the carat figure until the plating is confirmed |
| Cufflinks | "Silver cufflinks" | Rhodium plated base metal | Fix: "rhodium plated cufflinks" |
| Studs | "925 silver studs" | 0.8 g pair, 925 stamped | Check: underweight and stamped; confirm fineness evidence before keeping the claim |
The six rows above are the ones that raised a question. Across all twelve listings in this illustration, five needed word changes (four of them shown here) and one, the studs, needed evidence before its claim could stay. Every word change had the same shape: the model collapsed a precise term into a shorter, more attractive and less accurate one. Total time for the audit was about an hour, and all the fixes were word changes. The biggest result was a rule: from now on, every listing is drafted with the prompt block and checked against the "Metal claims used" line.
A realistic slip: the helpful bundle of synonyms
A seller asks an assistant to "make the product page more luxurious" for a plated bangle. The tool replaces "gold plated brass" in the second paragraph with "pure gold finish", writes "heirloom-quality precious metal" in the headline, and adds a care tip about "polishing your gold". None of those sentences contains the word hallmark, but each one tells a buyer the item is gold or contains precious metal.
It reached the live page because the seller had checked only the title. The remedy is to check every place metal can appear: the title, bullets, long description, image alt text, size and care sections, meta description, structured data and social captions. Run a search for the words gold, silver, platinum, palladium, sterling, solid, carat, ct, 375, 585, 750, 800, 925 and 999 across the finished text, and look at every hit.
Three shop types, three sets of risks
- A fashion jewellery shop selling plated and base metal pieces. The risk is colour words and plating terms. Almost every "gold" and "silver" in AI copy needs to become "gold tone" or "gold plated [base]". The banned-claims list above does most of the work.
- A shop selling hallmarked silver and gold. The risk is mixed-metal and weight details. Pieces made of silver and brass, or gold and silver, need descriptions of each part. Always include a photo of the hallmark, and make sure its fineness agrees with the text.
- A vintage or second-hand seller. Pre-owned pieces are covered. The pre-1950 exemption needs proof of date and fineness, so keep your evidence and avoid "antique gold" or similar unless you can show it.
The tutorial on AI tools for a jewellery business shows which tools suit each of these jobs, and the one on what AI gets wrong on metals and stones gives more examples of the wording errors.
Photos, alt text and imagery can imply metal too
Words are not the only claim. A close-up image of a stamp, an "18K" overlay on a banner, or alt text such as "solid gold chain" all describe the metal. When AI edits or generates product images, it may add a polished gold sheen to a base metal item or create a stamp that does not exist. Keep photos honest and true to colour; the tutorial on jewellery photography with AI covers it. If your AI tool writes alt text, run it through the same banned-claims list. And never let a generated image show a hallmark you have not got.
Stones are a separate list
The checks above are about metal. Stones raise a different set of claims: natural or lab grown, treated or untreated, simulant or genuine. AI copy gets those wrong as often as it does metals, and the checklist in lab grown diamond terminology for AI-written copy is the one to use. Keep the two lists in the same prompt block, so each listing is checked against both.
A second prompt: let AI check a finished draft against the list
Drafting and checking should be separate steps, ideally in separate chats, because a model that has just written a claim tends to defend it. Use a checker prompt on the finished text, then still read its output yourself.
Below is a finished jewellery product page and a PRODUCT FACTS block. Act as a strict
reviewer. List every phrase in the page that names or implies platinum, gold, palladium
or silver, a carat or fineness figure, a hallmark, "solid", "sterling", "genuine" or
"real". For each phrase, say: supported by PRODUCT FACTS (quote the line), not
supported, or ambiguous. Do not rewrite the page. Do not say whether it is legal.
PAGE:
[paste]
PRODUCT FACTS:
[paste]An illustrative result for a plated bangle page might list four phrases: "gold bangle" in the title (not supported, facts say gold plated brass), "18ct finish" in the second paragraph (not supported, no fineness given), "gold plated" in the specification (supported), and "polish your gold" in the care tips (not supported). That is a useful list, because each line points to a place to edit. It is not a judgement of legality, and the checker can miss things, which is why the final read is yours. Over a few weeks, count how often the checker catches something your own read missed. If it never does, you can drop it; if it does so more than once in twenty pages, keep it.
A sign-off step that takes two minutes per listing
- Open the supplier or maker specification and the hallmark photo next to the draft.
- Read the "Metal claims used" line the prompt produced. Tick each claim against the specification.
- Search the draft for the words in the list above and confirm each hit is covered.
- Check the images for any stamp or marking, and confirm it matches the text.
- Record the date, your initials and the weight and fineness you relied on, in a shared sheet.
That sheet is also your evidence if a customer, a marketplace or an enforcement officer asks how a claim was made. It should name the person who approved the listing, because the law is concerned with the person in the course of trade, not the tool that wrote the first draft. If you want help setting up the same check across several listing channels, the tutorial on building a banned-phrase list for AI writing shows how to keep it in one place.
Selling to buyers outside the UK, and keeping the rules current
The guidance covers the UK's own requirements. If you sell abroad, other countries have their own rules on how precious metals and plated jewellery may be described, and they differ in their marks, thresholds and wording. I have not covered them here. Check the requirements of each market you sell to, with the relevant authority or a specialist adviser, before you let the same AI-written copy run on every site.
Also check the date of any guidance you rely on. The notes used here are a November 2022 edition, and the Assay Offices and the British Hallmarking Council may update them. A quarterly reminder to open the current guidance, compare it to your banned-claims list and update the prompt block takes about half an hour, and keeps every listing built on the same rules.
Questions jewellery sellers ask about hallmarking and AI copy
Do I need to hallmark everything I sell as silver or gold?
Not everything. The Assay Offices' guidance says items below set weights are exempt: 0.5 g for platinum, 1 g for gold and palladium, 7.78 g for silver, measured on total metal weight. Pre-1950 items can also be sold as precious metal if you can prove the fineness and date. Always check the current list of exemptions.
Can I say 'gold plated' on a brass necklace?
Guidance allows terms such as gold plated, rolled gold and bonded gold for base metal items, but it does not allow a base metal item to be hallmarked. Keep wording factual, name the base metal if you know it, and do not use a fineness figure unless it is supported. Check the guidance on plating thickness and fineness.
Is 'gold tone' safe wording?
The guidance gives gold tone and gold coloured as examples of descriptions that are not misleading for base metal items, while calling a gold-coloured base metal watch a gold watch would be an offence. Use colour words that plainly describe appearance, and do not let AI shorten them to just gold.
Does the hallmarking law apply to online shops?
The guidance says the requirement applies to anyone in the course of trade or business with UK consumers, including e-commerce, distance selling, market stalls and shops. If you sell to UK buyers from elsewhere, check how it applies to you with an Assay Office or trading standards service.
Who is responsible if AI wrote the claim?
You are. The offence concerns the person in the course of trade who applies or supplies the description. A tool that wrote the sentence is not a defence, so every listing needs a human check against a banned-claims list before it goes live.
Further reads
- Can You Put Jewellery on an AI Model? Disclosure Rules for Sellers — Disclosure rules when jewellery is shown on an AI model.
- Jewellery Pricing Calculator With AI: Metal, Labour and Markup — Price metal, labour and markup with a calculator.
- ChatGPT Prompts for Jewellery Shops: 8 for Listings and Clients — Eight prompts for listings and client messages.
- Online Shop AI Mistakes That Hurt Trust and Conversions — Online shop AI mistakes that hurt trust and conversions.
- AI Listing Mistakes That Can Mislead Buyers, and How to Check — How AI listing errors mislead buyers, and how to check.
- AI for Jewellery Design: Concept Sketches to Client-Approved Renders — From concept sketches to client-approved renders.
- The Etsy App in ChatGPT: A Listing Checklist for Small Shops — Shoppers can tag @Etsy in ChatGPT to find listings, then click through to Etsy. What it means for your shop, and a checklist to make listings easier to match.
- AI Tools and AI Development: The Complete 2026 Guide — the AI hub, including every tutorial in the AI-for-business series.
Sources: Hallmarking Guidance Notes, information from the Assay Offices of Great Britain (November 2022 edition, hosted on GOV.UK, read November 2026), including the sections on exemptions, plated articles and describing precious metals; GOV.UK, Hallmarking: how businesses can comply with the law (Dealer's Notice); Hallmarking Act 1973 as described in that guidance.