Simple Platinum Hallmark Guide

Simple platinum hallmark guide

Platinum hallmarking was introduced in the UK in 1975 as a result of legislation brought about by the Hallmarking Act of 1973. Prior to this date, items containing platinum would often carry no markings or simply ‘Plat’ or ‘Platinum’ and would be of varying purity.

A typical platinum hallmark

All platinum items weighing more than 0.5 grams must now carry a valid hallmark when sold in the UK. The photo on the right shows a typical hallmark. A platinum hallmark will consist of 3 compulsory and 3 optional stamps.

This post is a simple platinum hallmark guide, which we hope you find useful. If you have platinum to sell, please see our up-to-date scrap platinum prices. We also publish our scrap gold prices and our scrap silver prices.

The three compulsory platinum marks

Sponsor Mark

Also referred to as the makers mark, the first stamp in the photo indicates who submitted the item for hallmarking. Each sponsor (maker) has their own unique stamp.

Fineness Mark

The third stamp in our example photo is the fineness mark. This tells you the precious metal content, expressed in parts per thousand. There are four recognised standards of platinum:

  • 850 (85% pure)
  • 900 (90% pure)
  • 950 (95% pure)
  • 999 (99.9% pure)

When identifying an item as being platinum, it’s important to check the shape and contents of the fineness mark. If the shape is anything other than what is shown below, it isn’t platinum. As you can see, our ring is 950 platinum.

Platinum fineness

Assay Office Mark

The assay office mark tells you which assay office tested and hallmarked your item. There are now four assay offices in the UK:

Assay Offices

Assay offices

 Optional platinum hallmarks

The following 3 marks are all optional. Under hallmarking legislation, there is no compulsorary requirement to show these additional marks, however they are often shown.

Traditional Fineness Symbol

If your platinum item has a purity of 950 or 999, it may display the traditional orb mark. In our example photograph, you can see the second stamp is the traditional fineness symbol.

Platinum fineness orb symbol


Date Letter

Date letters are optional and therefore not always seen (as in our example photograph). The date letter tells us the year the item was hallmarked. As date letters were standardised across all assay offices from 1975, it’s quite easy to read. Below is a chart of all date letters from 1975 onwards.

Hallmark Date Letters

Standardised UK hallmark date letters from 1975 onwards

International Convention Mark

An International Convention Mark is sometimes shown within the hallmark. It is a mark recognised by all member countries of the International Hallmarking Convention.

Platinum convention mark

Convention mark

Testing platinum

Without a valid hallmark, most jewellers and small scale gold buyers will not be able to accurately test the purity of platinum jewellery. Due to its inherent inertness, traditional ‘acid’ testing can only help determine if an item isn’t platinum, however you can’t for example differentiate 900 and 999 platinum.

High-end and specialist precious metal dealers use XRF (X-ray fluorescence) testing to accurately identify the platinum content of jewellery. Inductively coupled plasma, optical emission spectrometry is used by assay offices during the hallmarking process.

23 Responses to “Simple Platinum Hallmark Guide”

  1. Gab says:

    Hello Phill,

    Gab here again. It’s a confusing Lighter. Looking at the inscription and dents on its front you’d be inclined to think the lighter was platinum inside (we had been wondering if hidden under a brass coat to smuggle shortly after the war). But other signs indicate it is brass inside.

    The only consistent story we could come up with was that it was coated/recoated with platinum some time after gifting and getting damaged. This would explain why the dents are platinum rather than brass coloured.

    As you suggest, when I get a chance I’ll go see if someone can confirm with XRF if the remains of the coating are platinum.

  2. Gab says:

    I have just acquired a large vintage petrol lighter from Hungary, in Eastern Europe, that has an inscription stating it was originally gifted in 1948. After getting it home I discovered what appears to be a hallmark under the lift-arm. After some research it appears the stamp is the Platinum icon, a ball-crown in a pentagon. But I have found no other hallmarks. What do you think?

    Here’s a link to a photo I took of it:

  3. Geraldine Servier says:

    Dear Sir, Madam,
    I have an engagement ring with 5 very small stones on a silver coloured metal. The marks are H.S, 18CT, PLAT, 7375. Could you tell me what they mean please?
    G. S.

    • At a guess, this is an antique ring? HS will be the maker, the shank is probably 18 carat gold and the stones are probably mounted in platinum. 7375 doesn’t refer to anything associated with a typical hallmark.

  4. Patricia says:

    I purchased a ring with hallmark NF 925 is that a good purchase, and can you tell me more about it. I also purchased another ring with 999 costa ring. Tell me more about this.

  5. Anonymous says:

    Hello! I have earrings and they have stamp “plated”. It is platina or what? Thankyou

  6. John dow says:

    Hi there I have been handed down a piece of jewellery from a family member but it has no hallmarks at all. However I do believe it to be a platinum ring with 3 beautiful cut diamonds, can this be an item of age as it hasn’t got hallmarks at all..thx

    • Hello John, it’s possible – you’ll need a jeweller to take a look at it to confirm. The ring can be analysed using XRF (x-ray florescence) to confirm whether it’s Platinum. The stones can be easily tested to confirm whether they’re diamonds & the style of the cut will give a indication as to age.

  7. Anonymous says:

    I have a secondhand Platinum Engagement Ring that has no hallmarks on it at all, has this originated from the USA?


    • Phil says:

      Hello Lee, it’s impossible to determine the origin of your ring if there are no marks present. If it’s sent to us, we’ll X-Ray it to confirm its metal content & then issue you a formal valuation based on our current rates.

  8. debbie says:

    i have an old gold and platinum ring which is marked 18ct&ptl then 1992 do you know what this means?
    i know the 1992 is not the year as i have had it since 1987 and it was my grandmas before then

  9. Gail says:

    i have an oldish style pendant its silver/greyish in colour has mark 999 & i think its 99 and weighs 5grams. is it silver or platinum and could it be worth much.

  10. Claire Richards says:


    I have a ring with a trilogy of stones in it (glass or cz because they are rubbed and dull) but the ring is marked 9 ct plat…do you know what this means? Does it mean gold plated?


  11. David says:

    I have an interesting object that has a hallmark very similar to the sheffield mark above. Below that it says 95%. I could send picture. Can you help?

  12. Moaz says:

    I want to ask about platinum 900 100 pd alloye
    It’s good or no?
    And witch is better pt900 or pt 950

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March 14th, 2011 23 Comments » Hallmarks, Platinum |