Hallmark Guide
What Is a Hallmark? Meaning & UK Marks Explained
A hallmark is an official mark applied by an authorised UK Assay Office, confirming that a precious metal is the purity it claims to be. On solid gold, it independently verifies the exact carat.
In short: a hallmark is your independent, legal proof that a piece of gold is exactly the purity it claims to be — tested and stamped by a UK Assay Office, not by the maker. On solid gold, it's the difference between a piece that is said to be gold and one that is proven to be gold.
The Three Compulsory Marks
Every UK hallmark is made up of three compulsory symbols. Together they tell you who is responsible for the piece, how pure the metal is, and where it was independently tested.
| Mark | What it shows |
|---|---|
| Sponsor's mark | The registered maker or company that submitted the piece for hallmarking. Ours is CMJ. |
| Fineness mark | The metal's purity in parts per thousand — for example 585 for 14ct gold, 375 for 9ct and 750 for 18ct. |
| Assay Office mark | The independent office that tested and hallmarked the piece, such as the London Assay Office leopard's head. |
How to Read a Hallmark
A complete UK hallmark typically includes a sponsor mark, a fineness mark (such as 585 for 14K gold) and an assay office mark. For a full step-by-step explanation and placement examples, see the dedicated guide.
Read the full hallmark breakdownGold Fineness Reference Table
| Karat | Fineness | Gold Content |
|---|---|---|
| 9K | 375 | 37.5% gold |
| 10K | 417 | 41.7% gold |
| 14K | 585 | 58.5% gold |
| 18K | 750 | 75% gold |
| 22K | 916 | 91.6% gold |
| 24K | 999 | 99.9% gold |
Majestic Jewellery specialises in 14K gold (585), with 9ct and 18ct also available.
Majestic Jewellery Sponsor Mark
Our registered sponsor mark appears as CMJ. This identifies the responsible company that submitted the piece for independent hallmarking.
Independent Verification
Eligible pieces are submitted to the London Assay Office for independent testing and official UK hallmarking, so metal purity is externally verified rather than self-declared.
Learn about the London Assay Office processCommon Questions About Hallmarks
What does a hallmark mean?
It means the metal's purity has been independently tested and certified by an official UK Assay Office — an independent, legally-backed confirmation that the gold is exactly the carat stated, rather than relying on the maker's own word.
Does all gold jewellery have to be hallmarked?
In the UK, gold items over the legal weight threshold (1 gram for gold) must be independently hallmarked. Very light pieces can fall below the threshold and may be exempt.
Is 14ct / 14K gold real gold?
Yes. 14ct gold is 585 parts pure gold per thousand (58.5%) — solid gold all the way through, never plated. See our 14K gold purity guide.
How can I check my gold is genuine?
Look for the hallmark and read its three marks. If a piece is claimed to be solid gold but carries no hallmark (and is above the weight threshold), treat it with caution. Learn how to read a British hallmark →