Before you sell a gold item, it's worth knowing whether it's actually gold. When you know for yourself what you have, you can compare the offers you receive and make sure the price is right.
Identifying real gold is often easier than you'd think. Most of the tests only require tools you already have at home and a few minutes of your time. In this article we go through four practical tests that will give you a good picture of your gold.
A single test doesn't always give a definite answer. Final certainty always comes from a laboratory measurement — for example XRF X-ray analysis or an acid test.
1. Check the hallmarks first
Before you test the gold physically, look for hallmarks. In Finland and most European countries, gold items are marked with a hallmark showing the gold content.
The most common carat hallmarks:
| Hallmark | Carats | Purity |
|---|---|---|
| 333 | 8K | 33.3% |
| 585 | 14K | 58.5% |
| 750 | 18K | 75.0% |
| 916 | 22K | 91.6% |
| 999 | 24K | 99.9% |
Hallmarks are often small and hard to read — use a magnifying glass or your phone's camera. On rings, the hallmark is usually found on the inner surface; on necklaces, near the clasp; and on earrings, on the back.
If there's no hallmark, that doesn't necessarily mean the gold isn't real. Older items may never have been stamped, the mark may have worn away, or the item may be from abroad. But a missing hallmark is a reason to run further tests.
A word of caution: hallmarks can be forged. Especially with items bought online, a hallmark is no guarantee of authenticity. It's a good starting point, but not final proof.
2. The magnet test — simplest and fastest
Gold is not magnetic. This is one of its fundamental properties.
Get a strong magnet — a small fridge magnet won't do, you need a neodymium magnet, which you can buy at a hardware store for a few euros. Hold the magnet close to the gold item.
An important limitation: this test doesn't tell you how much gold is in the item. A gold-plated iron item will be attracted to the magnet, because there may be steel underneath a thin layer of gold. On the other hand, brass or silver won't react to a magnet either, even though neither of them is gold.
The magnet test is an elimination test: if the item reacts strongly, it isn't gold. If it doesn't react, further tests are needed.
3. The float test — density tells the story
Gold is extremely dense — denser than almost any other common metal. The density of pure gold is 19.3 g/cm³, roughly twice the density of lead. Real gold sinks quickly in water and never floats.
Fill a glass with water. Drop the gold item into the water.
A more advanced version is the water displacement method, which lets you calculate the item's density precisely:
- Weigh the item dry (note the weight in grams)
- Fill a measuring cup with water and note the volume
- Drop the item into the water and note the new volume
- The change in volume is the item's volume in cubic centimetres
- Density = weight ÷ volume
If the result is close to 19 g/cm³, it's likely genuine pure gold. 18-carat gold has a density of around 15–16 g/cm³ depending on the alloy metals, and 14-carat gold around 13 g/cm³.
This test isn't suitable for jewellery that contains stones or has hollow spaces inside.
4. Checking colour and wear
Real gold keeps its colour. It doesn't change over the years — it doesn't darken, turn grey, or rust.
Examine the item carefully:
- Worn spots: Are there areas where the surface layer has worn away? If you see a different-coloured metal underneath — usually silvery grey or a paler yellow — the item is gold-plated, not solid gold.
- Discolouration: Real gold doesn't darken. If the item has dark spots or greenish edges, it contains a significant amount of other metals.
- Colour consistency: A genuine gold item has an even colour across its whole surface. Variations in colour often point to plating.
This test is the roughest of the four, but it quickly tells you whether you're dealing with solid gold or plating. Wear marks are especially revealing on older items.
What to do once you've tested
If you've run these tests — the hallmarks are visible, the magnet doesn't attract it, the density is high and the colour is even — you can be fairly confident that you have real gold.
These four tests give you a solid foundation. You'll know what you have before you sell. You can compare the offers you receive against what you already know about your own gold.
Final precision always comes from the laboratory. At Gold Lab we use acid testing or XRF X-ray analysis.
In an acid test, a small mark from the item's surface is scraped onto a testing stone, and test acids calibrated for different carats are applied to it. The reaction gives a precise reading of the gold content. Our other method is XRF X-ray analysis, which measures the gold content to within a thousandth of a percent without damaging the item.