Hallmarking & Materials
Last updated: 19 August 2026
What Hallmarking Means
A UK hallmark is the official mark applied to qualifying precious metal jewellery by an authorised Assay Office. It confirms that the metal has been independently tested and certifies its purity.
Hallmarking protects customers. It is one of the oldest forms of consumer protection in the UK, ensuring that a piece described as silver, gold, platinum or palladium genuinely meets the stated fineness.
THE LAB Jewellers is registered with the London Assay Office and uses approved laser-marking processes for qualifying pieces.
UK Hallmarking Thresholds
Under UK hallmarking law, precious metal articles above the following weights must be hallmarked before they can be described as that metal:
- Silver: above 7.78g
- Gold: above 1g
- Platinum: above 0.5g
- Palladium: above 1g
Where UK hallmarking law requires it, qualifying THE LAB Jewellers pieces are submitted for hallmarking before dispatch.
A product will only be described as hallmarked where this is accurate and supported by assay evidence.
Dealer’s Notice
The Hallmarking Act 1973 requires registered dealers to display the official Dealer’s Notice issued by an Assay Office, explaining the approved hallmarks customers may encounter on UK jewellery.
Dealer’s Notice B, issued by the British Hallmarking Council and displayed in accordance with the Hallmarking Act 1973.
Metals We Use
THE LAB Jewellers works in the following solid precious metals:
- 925 Sterling Silver — 92.5% pure silver, alloyed for durability. A widely recognised standard for fine jewellery.
- 14kt Gold — 58.5% pure gold, hallmarked 585. The everyday sweet spot: more than half pure gold, with the durability for daily wear. Available in white, yellow and rose.
- 18kt Gold — 75% pure gold. Higher purity, richer colour, softer feel. Available in white, yellow and rose.
All metals we use are solid throughout the piece, not plated. White gold pieces are finished with rhodium, which may require periodic replating over time as part of normal care.
9ct vs 14kt — why we start at 14kt
Most jewellery on the UK high street is made in 9ct gold — the legal minimum that can be called "gold" in Britain. We don't use it. Every gold piece we make starts at 14kt.
- 9ct gold is 37.5% pure gold — hallmarked 375.
- 14kt gold is 58.5% pure gold — hallmarked 585 — around 56% more actual gold in every piece.
More gold means a richer, warmer colour, more precious metal in the piece, and better long-term value. And because 585 is an official UK hallmarking standard, the difference isn't a marketing claim — it's struck into the metal by the assay office. Check the hallmark on any piece: ours reads 585 or 750; the high street's usually reads 375.
Reading your hallmark
A full UK hallmark on a THE LAB Jewellers piece carries: our registered sponsor's mark, the millesimal fineness number (925 for sterling silver, 585 for 14kt gold, 750 for 18kt gold), the assay office mark (the leopard's head for London), and the date letter for the year of marking.
Lab-Grown Diamonds
Every diamond we set is lab-grown.
Lab-grown diamonds have the same essential chemical composition, crystal structure, hardness and optical properties as mined diamonds. Their quality can be independently documented: IGI issues detailed 4Cs grading reports for lab-grown diamonds. Their origin is laboratory-grown rather than mined.
This allows us to offer larger stones, higher quality grades and cleaner provenance at a more accessible price point than equivalent mined-diamond jewellery.
Certification
Every piece with a centre stone of 1.00ct or above — in silver or gold — comes with an individual IGI grading report as standard, at no extra cost.
The accompanying document confirms the stone’s laboratory-grown origin and records the quality information provided by the issuing laboratory.
Certification does not add to your lead time. A piece will only be described as certified where the relevant certificate exists and matches the supplied stone.
Product-Specific Evidence
Specific hallmark details, certification reports and material evidence for individual pieces are available on request. Email info@thelabjewellers.com if you would like documentation for a piece you have purchased or are considering.