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Counterfeit gold coins and bars exist. The most sophisticated fakes - typically tungsten-core bars coated in genuine gold - are designed to pass basic inspection. The good news is that verified purchases from established UK dealers carry essentially no risk of fakes, because dealers use professional verification equipment as standard. The risk concentrates in private purchases and informal markets.
This guide explains the main verification methods, what each test can and cannot detect, and how to buy safely.
Risk by purchase channel
| Channel | Fake risk | Notes |
|---|---|---|
| Established UK bullion dealer | Very low | Dealers verify all stock. Regulated for AML. |
| Royal Mint direct | Negligible | Minting and selling through the same organisation. |
| eBay / private sales | Moderate to high | No verification. Fakes do appear. |
| Antique dealers / auctions | Low to moderate | Depends on the seller’s expertise and processes. |
| Informal markets / cash sales | High | Unverified, no recourse. |
The main types of fake
Tungsten-core bars: Tungsten has almost the same density as gold (19.3 g/cm³ each). A bar drilled out and filled with tungsten can pass a weight test. XRF detects this from the surface; ultrasound is more reliable for larger bars where the tungsten core sits deep.
Gold-plated base metal coins: Thinner gold layer over a base metal coin of similar size. Often detectable by weight, dimensions, and the ping test. Less sophisticated than tungsten fakes.
Low-purity alloys presented as fine gold: Coins or bars that are partly genuine gold but at lower fineness than claimed. Requires chemical or XRF testing to detect.
Counterfeit coin designs: Coins designed to look like Sovereigns or Britannias but containing less gold. Detectable by weight, dimensions, and examination of edge and design details.
Verification methods
1. Weight test
What it detects: Most base-metal fakes. Not effective against tungsten-core fakes.
A Full Sovereign weighs exactly 7.98g (±0.01g). A 1oz gold bar weighs 31.103g. A 1oz Gold Britannia weighs 31.21g total (31.10g fine gold in 999.9 alloy, plus a negligible amount of other content in the capsule seal).
A precision scale accurate to 0.01g is inexpensive and catches most crude fakes. Weigh against published specifications.
2. Dimensions test
What it detects: Coins or bars with incorrect size - useful alongside weight.
A Full Sovereign is 22.05mm diameter and 1.52mm thick; a 1oz Gold Britannia is 32.69mm diameter and 2.80mm thick; a 1oz PAMP bar runs approximately 41 × 24 × 2mm. Any significant deviation from these is a red flag.
Verify with digital calipers (around £10 from any hardware store).
3. The ping test
What it detects: Base-metal or tungsten-core fakes.
Strike the coin lightly with another coin or a pencil while holding it loosely. Genuine gold produces a clear, sustained ringing tone - higher-pitched and longer-lasting than copper or silver equivalents.
A coin containing significant non-gold material produces a dull thud or short ring.
This test is useful, simple, and free. It is not infallible - some high-quality fakes can produce a reasonable ring - but it catches most crude counterfeits.
4. Acid test
What it detects: Gold purity and presence of gold surface coating.
The acid test uses nitric acid applied to a scratch of the coin or bar surface. Gold of different purities reacts differently. The reaction pattern indicates fineness. A gold-plated fake will show the base metal’s reaction on the scratch surface.
This is a destructive test - it leaves a small mark on the coin. Most buyers only use it on bars, not on coins where surface quality may matter. Acid test kits cost £10–£30.
5. XRF (X-ray fluorescence) testing
What it detects: Surface composition with high accuracy. Not reliable for detecting tungsten cores behind a thick gold layer.
XRF guns fire X-rays at the metal surface and read the fluorescent energy returned - identifying elemental composition to within 0.01% in seconds. Dealers use handheld XRF devices routinely, and most will test a coin or bar for you on request, sometimes free of charge.
XRF is the standard verification tool at UK bullion dealers. It does not penetrate deeply - a sophisticated tungsten-core bar with a thick gold cladding can defeat surface XRF. For large bars, ultrasound or fire assay is more reliable.
6. Magnetic test
What it detects: Ferrous metal content.
Gold is not magnetic. A strong rare-earth magnet (neodymium) will not attract genuine gold. If a coin or bar is attracted to a magnet, it contains ferrous material and is not pure gold.
This is a negative test - passing it does not prove authenticity, but failing it definitively proves the metal is not pure gold.
7. Ultrasound testing
What it detects: Internal structure. The most reliable method for detecting tungsten-core bars.
Ultrasound devices measure how sound waves travel through the metal. Tungsten’s acoustic properties differ from gold. This is the professional standard for verifying large gold bars, particularly 400oz Good Delivery bars. Not typically available to retail buyers, but offered by some specialist services.
Which method for which product?
| Product | Practical tests | Notes |
|---|---|---|
| Sovereign or Britannia | Weight + dimensions + ping + magnetic | These four together catch virtually all fakes at coin level |
| Small gold bar (1oz–100g) | Weight + dimensions + XRF (at dealer) | Assay cards with serial numbers add confidence |
| Large bar (250g–1kg) | XRF + ultrasound | Specialist testing recommended for high-value bars |
| Second-hand purchase | All of the above | Extra scrutiny warranted |
How to buy safely from the start
Buying from an established, long-trading UK bullion dealer eliminates the need for the buyer to verify independently. Reputable dealers verify every coin and bar before reselling.
For private purchases (eBay, inheritance, private seller):
- Check weight against published specifications
- Check dimensions with calipers
- Do the ping test
- Use a strong magnet
- For bars: examine the assay card and bar serial number (search online - some dealers publish serial number registers)
- For anything above £1,000: take to a professional dealer for XRF verification
How people usually decide
If you buy from an established UK bullion dealer, you will almost certainly never need to verify anything yourself - the dealer tests everything that comes into stock. The seven methods above are for every other scenario: coins received as a gift, pieces from an inheritance, items bought at auction or from private sellers.
One practical point many people miss: paying by bank transfer rather than cash creates an audit trail if something does go wrong. It’s simple protection that costs nothing and matters if you ever need recourse.
Frequently asked questions
Can a gold coin pass the weight test but still be fake? Yes - tungsten-core coins or bars can be machined to the correct weight because tungsten’s density is close to gold’s. The weight test catches crude fakes but not sophisticated tungsten-core counterfeits. The ping test and XRF add further confidence.
Should I test coins bought from a reputable dealer? Not routinely - the dealer has already verified them. If you have any reason for doubt (unusual purchase circumstances, coin arrived damaged in transit, etc.), testing is reasonable.
Where can I get gold professionally verified? Most established UK bullion dealers will verify a coin or bar for a small fee - or sometimes free. Contact Chards, Atkinsons, Sharps Pixley, or Hatton Garden Metals and ask.