How to Authenticate Gold Jewellery Before You Buy

Start With the Hallmark

Find the hallmark first — it may be inside the ring band, on the clasp, on the back of a pendant, or inside a watch case back. The fineness mark (375/585/750/916/999) must match the seller's claim. Pre-1973 UK pieces use older hallmark formats; cross-check with the assay office's guides if the marks look unfamiliar.

Physical Tests

Magnet test: gold is not magnetic. A magnet catching the piece reveals gold-plated steel. Weight test: gold is dense (19.3g/cm³). A piece that feels light for its size is suspicious. Visual inspection: worn plating shows at edges and high points; under a 10x loupe, a different metal colour at the wear points is decisive.

Acid Testing

Jewellers' acid test kits cost £20–30 and are definitive. Scratch a small line on a testing stone, apply a drop of the relevant acid, and the reaction (or lack of it) confirms karat. For high-value pieces, have a jeweller do this rather than risk the piece yourself.

Signed Piece Authentication

Cartier, Tiffany, Bulgari, Van Cleef & Arpels and Georg Jensen all offer authentication services. For a fee they will verify a piece and issue documentation. For gold watches, send the reference and serial to the manufacturer — most have online verification or a service-centre contact for confirmation.

Professional Route

Any piece over £500 justifies an independent valuation from an FGA (Fellow of the Gemmological Association) or RICS-registered valuer. The £30–100 fee protects the purchase. Reputable dealers will allow inspection or a cooling-off period before the sale closes.

Authentication-Free Alternative

If you want gold exposure without the authentication burden, buy bullion from an established dealer like SilverGoldBull. Sealed and assayed bars or sovereign coins arrive with certification and need no separate authentication.

Frequently Asked Questions