Someone offers you a gold chain. Maybe you inherited it. Maybe you bought it second hand. Maybe a market stall price felt too good to be true and now it is sitting on your kitchen table, and you are not entirely sure what you have.
Five tests will tell you almost everything you need to know. Four of them need nothing more than items you already have at home. The fifth is the one you use when the others leave any doubt.
Manna Jewellers in Birmingham's Jewellery Quarter carries out professional gold testing in the workshop, including XRF analysis and acid testing, for anyone who needs a definitive answer. Browse the gold chain collection if you want to buy something you can trust from the start.
The hallmark is the single strongest indicator. Look inside the clasp for 375 (9ct), 585 (14ct), or 750 (18ct).
Real gold is not magnetic. If a strong magnet pulls at the chain, it contains iron or steel.
A real gold chain will not leave green marks on your skin. Green marks mean copper or brass underneath.
Real gold sinks immediately in water. Anything that floats or drifts is suspicious.
No single home test is definitive. Use two or three together for a reliable result.
Professional XRF testing gives an exact purity reading in seconds without damaging the chain.
This is always the first thing to look at, and it takes about ten seconds.
Look inside the clasp or on the small tag near it. In the UK, all gold jewellery over one gram sold since 1973 must carry an official hallmark from a UK Assay Office. That hallmark includes a fineness mark: 375 for 9ct, 585 for 14ct, 750 for 18ct, 916 for 22ct. If any of those numbers are stamped clearly and legibly, that's a strong sign the chain is real.
Markings that say GP (gold plated), GF (gold filled), or GEP (gold electroplated) mean the chain has a gold coating over a base metal, not solid gold throughout. No mark at all doesn't automatically mean fake; some antique pieces predate modern hallmarking law, but it does mean you need to keep testing.
A poorly stamped, crooked, or suspiciously faint mark is a red flag. Counterfeit chains sometimes carry stamped numbers placed in unusual positions or slightly off the correct format for UK hallmarks.
Expert tip: The British Jewellers Association's guidance on hallmarking law confirms that under the Hallmarking Act 1973, all precious metal articles above minimum weight thresholds must be independently tested and hallmarked by a UK Assay Office before sale. The manufacturer does not apply a genuine hallmark. It is applied after independent testing. If a chain was legally sold in the UK, that mark should be there.
Gold is not magnetic. That is the whole test.
Get a strong magnet, a neodymium magnet from a hardware store, not a fridge magnet. Hold it close to the chain and move it slowly across the links and clasp. If the chain pulls toward the magnet, it contains iron or steel and is not solid gold. Real gold has no reaction at all.
One limitation: some fake chains use non-magnetic metals like brass or aluminium, which also pass the magnet test. So passing does not confirm a chain is real. Failing does confirm it is not solid gold.
Wear the chain against your skin for a couple of hours, somewhere warm where you might sweat. Then check for green or black marks.
Real gold does not react with skin. Green marks come from copper oxide forming when a base metal reacts with the acids and moisture in your skin. If the chain leaves a green mark, the metal underneath is copper or brass. The chain is plated, not solid gold.
This process takes time, not effort, and is one of the more reliable home methods because it directly reveals what sits beneath the surface.
Fill a glass with water. Drop the chain in.
Real gold is very dense and sinks immediately. A chain that floats, drifts slowly, or bobs near the surface is almost certainly not solid gold. Gold's density is around 19.3 grams per cubic centimetre, far heavier than the base metals used in fake chains.
Hollow gold chains still sink, just not as dramatically as solid ones. A slow sink does not automatically mean fake, but anything that stays near the surface does.
Every home test has limits. Two or three used together give a much more reliable picture, but for a chain of real value, take it to a professional.
Jewellers use two main methods. Acid testing applies a small amount of acid to a scratch mark from the chain and reads the reaction to identify gold purity by carat. XRF testing (X-ray fluorescence) is non-destructive: it determines the exact metal composition without scratching or damaging anything, and gives a precise purity reading in seconds.
At Manna Jewellers, the workshop team can carry out gold testing and valuation. Book an appointment to have a chain assessed in person.
|
Test |
What you need |
What it tells you |
Limitation |
|
Hallmark check |
Good lighting, magnifying glass |
Confirmed UK-hallmarked gold |
Worn or fake stamps possible |
|
Magnet test |
Strong neodymium magnet |
Fails if it contains iron or steel |
Non-magnetic base metals also pass |
|
Skin test |
Time |
Reveals copper or brass underneath |
Takes a few hours |
|
Float test |
Glass of water |
Dense real gold sinks immediately |
Hollow chains sink slowly |
|
Professional test |
A jeweller |
Exact purity percentage |
Requires a visit |
Start with the hallmark inside the clasp, looking for 375, 585, or 750 stamped clearly. Then run the magnet test with a strong neodymium magnet: real gold won't react. Wear the chain against your skin for a couple of hours and check for green marks. Use two or three tests together rather than relying on one alone for a more reliable result.
A UK hallmark includes a fineness mark showing gold purity as a three-digit number: 375 for 9ct, 585 for 14ct, 750 for 18ct. It also includes a sponsor's mark and the UK Assay Office mark for the assay. These appear on the clasp or a tag near the clasp. Markings like GP, GF, or GEP indicate gold plating over a base metal, not solid gold.
A fake chain with a copper or brass base often leaves green marks after wear, caused by a reaction between the base metal and skin acids. Real solid gold does not react this way. Some fake chains use non-reactive base metals that also do not leave marks, so the skin test works best alongside the hallmark and magnet tests.
Real gold sinks immediately because of its high density, around 19.3 grams per cubic centimetre. A chain that floats or drifts slowly is almost certainly not solid gold. Hollow gold chains still sink, just less dramatically than solid ones, so a slow descent is not automatically a sign of fake gold.
Professional XRF testing gives the most accurate result. It determines the exact metal composition without damaging the chain and produces a precise purity reading in seconds. Acid testing is the traditional professional method and also highly reliable. Both are available from reputable Jewellery Quarter jewellers and are more accurate than any home test.
Manna Jewellers has been in Birmingham's Jewellery Quarter for over 40 years. The team carries out gold testing, valuation, and professional inspection in the on-site workshop at Hockley Street. The gold chain collection covers curb, Figaro, rope, belcher, spiga, Venetian, and Franco styles in 9ct and 18ct yellow, white, and rose gold, all hallmarked and hand-finished in the workshop. Manna also buys and part-exchanges pre-owned jewellery, subject to inspection and valuation. Book an appointment to have a chain tested or browse the collection in person.
The complete guide to gold chain styles: curb, Figaro, rope and more: once you have confirmed a chain is real gold, or if you are buying new, this guide covers every main chain construction and which styles work best for pendants versus plain wear.
9ct vs 18ct gold chains: which should you choose?: once you know a chain is real, the carat matters. This guide explains what the fineness numbers mean, how they affect colour and durability, and which carat suits which use.
The timeless craft: how gold is reused in jewellery making: covers how Manna tests gold purity before remelting using XRF analysis and acid testing, the same professional methods used to verify a chain's authenticity.
