How to Tell a
Trustworthy Jeweller

Start With the Hallmark

In the UK it is illegal to sell an item described as gold, silver, platinum or palladium above a certain weight unless it carries a hallmark from an independent assay office. For gold that threshold is one gram, which covers every engagement ring you will ever look at. This is not a quality mark the jeweller awards themselves. The metal is tested and struck by one of four UK assay offices: London, Birmingham, Sheffield or Edinburgh.

A full UK hallmark tells you who submitted the piece (the sponsor's mark), what the metal is and its purity (750 for 18ct gold, 950 for platinum), and which office tested it. Ask to see it under the loupe; any jeweller will show you. Jewellers selling hallmarked goods are also required to display a dealer's notice explaining the marks, usually near the till. A shop that sells "18ct gold" rings with no hallmark and no explanation has already failed the first test, and it is the only test with the force of law behind it.

Certificates, and How to Check One

Any diamond of meaningful size should come with a grading report from an independent laboratory. For natural diamonds, GIA is the standard the whole trade defers to. IGI is widely used and broadly accepted for lab-grown stones, and HRD is a reputable European lab you will also see. What matters is independence: a certificate issued by the shop itself is a description, not a grading report.

Here is the part few buyers know: reports are verifiable online, free, in under a minute. GIA's Report Check and IGI's verification page both let you type in the report number and see the full grading. The number is on the certificate, and on most GIA-graded stones it is also laser-inscribed on the girdle of the diamond itself, which the jeweller can show you under magnification. If the report number does not match the stone in front of you, or the jeweller is reluctant to let you check, you have learned what you needed to know.

One caution in the other direction: a certificate grades the stone, it does not price it. Two stones with identical grades can differ in beauty, and a certificate is not a substitute for looking. The 4Cs guide covers how to read what a report is telling you.

The Paperwork That Matters

A written quote or receipt that describes the ring. Metal and purity, stone type, carat weight, grades, certificate number. A ring described only as "diamond ring" on the receipt is a ring you cannot insure properly, resell honestly, or complain about accurately. Good jewellers write detailed descriptions without being asked.

The returns policy, in writing, before you pay. This one surprises people: if you buy in a physical shop, you have no automatic legal right to return a ring because you changed your mind. Only faulty or misdescribed goods must be taken back. Any goodwill returns window is the shop's own policy, so find out what it is and get it in writing. Buying online is different: distance selling rules give you fourteen days to cancel most purchases, though genuinely bespoke commissions made to your specification are excluded. This is worth understanding before the purchase rather than after.

The company itself. Two minutes on the Companies House website tells you how long the business behind the shop has existed. A jeweller trading for decades under the same name has something to lose. Insurance valuations, resize policies and workshop guarantees are all worth asking about; the pattern you are looking for is a business that answers these questions readily, because the trustworthy ones always do.

Red Flags in the Room

Some warning signs are reliable enough to act on immediately.

A discount that only exists today. "This price is if you buy now" is pressure dressed as generosity. Real prices survive a night's sleep. Walk.

Reluctance to put anything in writing. A jeweller who will say a number but not write it down is telling you the number changes depending on who asks.

No certificate, or an in-house one, on a significant stone. The absence has a reason, and the reason is rarely in your favour.

You feel steered past your stated budget. The best jewellers work to the number you gave them. Being repeatedly shown rings above it is a sales technique, not a service.

The street tout. In Hatton Garden specifically, being approached on the pavement and invited upstairs is an experience many buyers describe, and it is not how the good houses win business. Our Hatton Garden guide covers how to navigate the district well.

None of these mean a shop is dishonest. All of them mean you should buy somewhere else, because in London you never need to tolerate them. There are hundreds of jewellers in this city; scarcity is not the buyer's problem.

Reading the Review Record

Star ratings compress too much into one number, so read the record instead. Volume and history matter: a 4.9 across nine hundred reviews spanning eight years is evidence, a 5.0 across twenty recent reviews is a start. Read the critical reviews first, and watch how the business replies to them; a defensive or absent response to a genuine complaint tells you about the aftercare you would get. And weigh what the positive reviews actually describe. Hundreds of accounts of patience, resizing handled well, and buyers who felt no pressure are describing behaviour, which is harder to fake than a star.

That, at scale, is what this site does. Our Top 100 ranks every verified London jeweller on the strength of its full review record, and we have read the complete Google review text behind the ranking: over 38,000 reviews. The no-pressure list and the first-time buyers list are both built by counting what customers actually wrote, and every count on them can be checked against the source reviews. How we work, and what we refuse to take money for, is set out in the editorial policy.