Counterfeit gold ranges from cheap gold-plated base metal to sophisticated bars with tungsten cores. Fortunately, several practical tests can flag a fake long before money changes hands. None is perfect alone, so combine a few, and confirm anything serious with a professional.
1. Check the hallmark
Genuine gold is usually stamped with a hallmark indicating its purity, such as a karat number or a fineness figure like 999 or 750. Examine it with a loupe: authentic marks are crisp and consistent, while fakes are often blurry, shallow, or misaligned. A missing hallmark is not proof of a fake, but its absence warrants extra caution.
2. The magnet test
Gold is not magnetic. Hold a strong magnet near the item: if it pulls, attracts, or sticks, the piece contains magnetic metals like iron or nickel and is not solid gold. The catch is that some counterfeits use non-magnetic base metals, so passing this test alone does not confirm authenticity.
3. The density (water displacement) test
Gold is remarkably dense — far denser than most metals used to fake it. Weigh the item in grams, then measure how much water it displaces in millilitres. Dividing weight by volume gives density; pure gold sits near 19.3 g/cm³. A reading well below that suggests the piece is hollow or made of lighter metal. This test is powerful because density is very hard to fake without an equally dense (and expensive) substitute.
4. The ceramic scratch test
Drag the item gently across an unglazed ceramic tile. Real gold leaves a gold-colored streak, whereas pyrite or plated fakes often leave a black or greenish mark. Because this can lightly mark the item, use it cautiously and only on pieces you are willing to test.
5. The acid test
Jewelers use small bottles of acid calibrated to different karats. A tiny scratch on a testing stone is exposed to acid; genuine gold of the stated karat resists, while lower-purity or fake metal reacts and dissolves. The acid test is reliable for surface purity but can be fooled by gold-plated items, and the acids are corrosive, so handle with care or leave it to a professional.
6. Professional assay
For absolute certainty — especially with bars or high-value pieces — a professional assay is the gold standard. Techniques such as X-ray fluorescence (XRF) read the exact metal composition without damaging the item, and ultrasonic testing can detect a hidden tungsten core inside a bar. Any reputable dealer or assay office can perform these.
Putting the tests together
No single test is foolproof, so think in layers:
- Quick screen — hallmark and magnet rule out the crudest fakes.
- Stronger check — density catches most hollow or substituted pieces.
- Confirmation — acid or a professional XRF assay settles any doubt.
The best protection is prevention: buy from reputable dealers, keep original assay cards and receipts, and stick to recognized brands. Knowing the live metal value also helps — if a price seems too good to be true, it usually is. Check what genuine metal should cost with our gold calculator before you buy.