Knowing what to ask for is the difference between hoping and knowing. These are the organisations whose certifications, hallmarks and reports we encourage every buyer in Hatton Garden to look for before they commit.
A UK hallmark is the only legal mark for precious metal, applied by one of the four UK Assay Offices where required by law.
A laboratory report (GIA, IGI, HRD, SSEF, Gübelin and similar) is a respected expert grading or identification, not a UK legal hallmark.
Trade membership (NAJ, RJC, London Diamond Bourse) shows professional standing, not a government guarantee.
A lab-grown diamond must be described clearly as "laboratory-grown" or "laboratory-created", never just "diamond".
British institutions and trade associations that signal legal compliance and professional standing.
Oversees the UK hallmarking system; only the four UK Assay Offices may apply a UK hallmark.
London, Birmingham, Sheffield and Edinburgh: the four offices legally authorised to hallmark precious metals.
A historic London institution that has championed the craft and run hallmarking for centuries.
The UK's leading jewellery trade association; members follow its code of conduct.
Britain's gemmological body and one of the oldest gem and jewellery education providers in the world.
A UK diamond trade bourse, recognised by the UK government and a member of the WFDB.
A leading UK authority for jewellery, watch and silver valuers (part of the NAJ).
An independent UK and Ireland body for professional jewellery, gemstone and watch valuers.
Global bodies that set trade standards and responsible-sourcing expectations.
The primary international jewellery, gemstone and precious-metals association.
The global standards body for responsible sourcing, from mine to retail.
The official organisation of the international diamond trading sector.
Represents the industry within the Kimberley Process for natural-diamond integrity.
Regulates the rough-diamond trade to help prevent conflict diamonds (not a retail grading report).
Independent laboratories that grade a diamond on cut, colour, clarity and carat. These are expert reports, not legal hallmarks.
Top-tier natural-diamond grading and gemmology; reports verifiable on GIA Report Check.
Very common for natural and lab-grown diamonds, with online report verification.
Recognised European diamond grading and authentication.
Grades loose natural, untreated diamonds.
Technology-led diamond grading and light-performance reports.
Diamond, jewellery and gemstone reports with online verification.
A light-performance supplement to GIA reports (AGS Laboratories closed in 2022).
Specialist laboratories for sapphires, rubies, emeralds, spinel, jade and pearls, where origin and treatment matter most.
Leading reports for coloured stones, pearls and diamonds.
High-value coloured-stone origin and treatment reports.
Ruby, sapphire, emerald and spinel origin reports.
Coloured-stone origin and enhancement reports.
A respected niche lab for ruby, sapphire and spinel.
Identification and origin reports for coloured stones.
Hatton Garden Jewellers lists these organisations as a reference, so you know whose names to look for and what each one actually tells you. Jewellers here may hold recognised trade memberships, professional valuation credentials and independent laboratory reports, and precious metal must carry a UK hallmark from an Assay Office wherever UK law requires one. Reports from laboratories such as GIA, IGI, HRD Antwerp, De Beers Institute of Diamonds, SSEF, Gübelin and GRS are expert grading and identification: a different assurance from a hallmark, and worth having in its own right. We are an independent directory, so the guidance here is our own and we reference these standards purely to help you buy well.
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