Fake gold is best caught by combining several checks rather than relying on one. At home you can check weight, dimensions, markings and whether the item reacts to a magnet, but only a professional with equipment such as an XRF analyser, ultrasound or a fire assay can confirm that gold is genuine all the way through.
What fakes look like today
Knowing what you are up against is half the job. The most common types are:
- Gold-plated copies of coins – Sovereigns, Krugerrands and Britannias struck in brass or copper with a thin gold layer. They are often slightly the wrong weight or size.
- Tungsten-filled bars – tungsten is almost exactly as dense as gold, so the weight looks right. The bar is wrapped in real gold, which also fools surface tests.
- Jewellery with false stamps – a “9K” or “18K” stamp on plated silver or base metal.
- Fake packaging and assay cards – copies of well-known refiners’ cards holding a counterfeit bar.
Checks you can do at home
None of these proves an item is genuine. They can only show that something is wrong.
1. Weight and dimensions
This is the most useful home check. You need digital scales accurate to 0.01 g and a pair of callipers. Compare the readings with the official specification:
| Coin | Weight | Diameter | Fineness |
|---|---|---|---|
| Sovereign | 7.98 g | 22.05 mm | 916.7 |
| Britannia 1 oz (from 2013) | 31.21 g | 32.69 mm | 999.9 |
| Krugerrand 1 oz | 33.93 g | 32.77 mm | 916.7 |
A one-ounce coin that is several tenths of a gram out is a serious warning sign. Old circulated Sovereigns may be very slightly worn, but genuine coins lose remarkably little weight.
2. Magnet
Gold is not magnetic. If an item jumps to a strong neodymium magnet, it contains iron, nickel or cobalt. If it does not, that proves nothing: copper, brass and tungsten are not magnetic either.
3. Sound
A genuine gold coin gently tapped against another coin gives a long, clear ring, while plated base-metal copies tend to sound dull. You need a known genuine coin to compare against, so treat this as a hint only.
4. A close look
Use a 10x loupe on the design, lettering and edge. Fakes often have soft detail, uneven lettering or a poorly finished milled edge. Since 2021 the Britannia has carried security features such as a latent image that switches between a padlock and a trident, micro-text and surface animation, which are hard to copy well. On jewellery, look where it rubs: a different colour showing through means plating.
Bars deserve extra care because a single piece can be worth thousands of pounds. Check that the refiner’s name, weight, fineness and serial number are stamped cleanly and match the assay card or invoice. A bar whose stamping looks shallow, blurred or uneven, or whose edges look like a seam between two layers, should be tested before you rely on it.
What not to do at home
Avoid scratching, filing, drilling or using acid kits on coins and bars. They reduce value and only test the surface. The water displacement (density) test will not catch tungsten either, because tungsten (19.25 g/cm³) is almost as dense as gold (19.32 g/cm³).
How a professional tests gold
Dealers, jewellers and pawnbrokers use equipment that gives a more reliable answer:
- XRF analyser – reads the metal composition in seconds without damaging the item. It only measures the surface, so it cannot see a tungsten core under a thick gold shell.
- Ultrasound – sound travels at different speeds through gold and tungsten, so a hidden core shows up.
- Electrical conductivity testers – check the metal beneath the surface of coins and bars.
- Fire assay – the most accurate method, but it destroys a small sample. It is mainly used for scrap and refining.
If in doubt, ask a dealer to test the item in front of you. Many established UK dealers test as standard when buying back.
Special points for jewellery
Jewellery fakes are usually plated items or pieces of lower purity than claimed:
- Hallmark – genuine UK gold jewellery over 1 g should carry a sponsor’s mark, fineness mark and assay office mark. A lone “9K” stamp is not a UK hallmark.
- GP, GF, RGP or HGE – plated or rolled gold, containing very little gold.
- 925 on a yellow item – gilded silver, not gold.
- Weight against size – gold is very heavy. A chunky chain that feels light may be hollow or another metal.
A jeweller can test purity with acid on a touchstone using a tiny, discreet sample. Leave this to a professional: the acids are hazardous.
Reducing the risk when you buy
- Buy from established dealers with a physical address and track record. You can compare them on our UK bullion dealers page.
- Prefer bars from refiners on the LBMA Good Delivery list and coins from national mints such as The Royal Mint.
- Keep invoices and certificates, and check that the serial number on a bar matches its card.
- Be wary of prices clearly below the market. Compare with live UK gold prices.
- Pay by a traceable method rather than cash.
The highest risk comes from private sellers online, at fairs and in classified ads. If you think you have been sold counterfeit gold, keep everything, get an independent test and report it to Report Fraud (the service that replaced Action Fraud in England, Wales and Northern Ireland; in Scotland, contact Police Scotland on 101); if a trader was involved, the Citizens Advice consumer service can refer the case to Trading Standards.
Bottom line
Home checks (weight, dimensions, magnet, loupe) catch crude fakes but not well-made tungsten-filled bars. Reliable confirmation comes from professional testing with XRF, ultrasound or assay. Buying from established dealers and keeping paperwork lowers the risk.
Sources: LBMA – Good Delivery List (gold) · The Royal Mint · Report Fraud
This is general information, not tax or investment advice.
Frequently asked questions
Is real gold magnetic?
No. If an item sticks to a magnet it contains another metal, but passing the magnet test does not prove it is gold, because copper and tungsten are not magnetic either.
Can a density test detect fake gold?
It catches crude fakes but not tungsten-filled bars, because tungsten is almost exactly as dense as gold.
How much should a genuine Sovereign weigh?
A full Sovereign weighs about 7.98 g and measures 22.05 mm across. It contains about 7.32 g of pure gold.
Where can I get gold tested in the UK?
Established bullion dealers, jewellers and the UK assay offices offer testing. Many dealers test items as standard when buying them back.
