How does a buyer check whether gold is real?
A stamp is a claim, not proof. Stamps are faked, and plated work sometimes carries a neat 585. That is why every serious buyer measures for himself – this is how that goes.
The magnet: what it does and does not say
Gold, silver and platinum are not magnetic. If your piece of jewellery sticks to a strong magnet, there is iron or nickel in it and it is certainly not solid precious metal.
The other way round the magnet proves nothing: copper, brass and lead are not magnetic either. It is a first sieve, no more – and it is the only test you can safely carry out at home yourself.
The acid test: quick, cheap, and it leaves a mark behind
In an acid test the valuer rubs the piece over a touchstone and puts a drop of nitric acid of a known strength on the streak. If the streak stays, the metal reaches that fineness; if it dissolves, it does not.
The test takes a few seconds and is accurate enough to tell 585 from 750. The drawback: it removes a minute amount of material and works only at the surface. A plated object with a thick layer can pass an acid test.
An acid test is not something you do yourself. It involves concentrated nitric acid, and the wrong strength will damage your piece of jewellery permanently.
Specific gravity: the density betrays the core
Pure gold has a density of 19.32 grams per cubic centimetre – almost two and a half times as heavy as steel. By weighing an object dry first and then submerged in water, the density simply falls out.
That is the test that finds what cannot be seen at the surface: a gold bracelet with a core of copper or tungsten has the right colour and passes the acid test, but never the density measurement. Tungsten lies close to gold in density, and for that very reason we always combine this measurement with X-ray.
X-ray analysis (XRF): the measurement without damage
In X-ray fluorescence the object is briefly irradiated, and each element sends back its own radiation as it does so. From that the instrument reads off the composition, accurate to tenths of a per cent, in a few seconds and without leaving a scratch behind.
XRF has one limitation of its own: it measures the top layer of the material, about a tenth of a millimetre deep. That is why the weighing in water stays alongside it as a check with larger, solid pieces.
- Magnet – rules out iron and nickel, nothing further.
- Acid test – quick and reliable at the surface, leaves a trace.
- Specific gravity – looks right through the object, needs a solid piece.
- XRF – accurate composition, no damage, only the outer layer.
Why we usually use two of them
No single method covers everything. A combination does: XRF tells you what is on the outside, the density tells you whether that holds for the core as well. Where there is doubt, a third test goes over it.
You stand there and watch along. We say the measured fineness out loud, and that fineness is precisely what the offer is based on.
- Troy ounce, gram and carat: the units side by sideThe world market reckons in troy ounces, your scales in grams and your jewellery in carats. With these three conversions you can check any offer yourself.Read on
- Krugerrand, Maple Leaf or Philharmonic: which one sells fastest?All three contain exactly one troy ounce of fine gold. What you get for them still differs – that lies in how well known they are, the fineness and how easily they scratch.Read on
- Selling a diamond without a certificate: what does it cost you?Without a GIA or HRD report a buyer has to judge for himself, and uncertainty translates into a lower offer. How much that differs, and when applying for a certificate pays off.Read on
Questions about how does a buyer check whether gold is real
Does testing damage my jewellery?
X-ray and weighing do not. An acid test leaves a small streak in an inconspicuous place; we only do that when it is necessary and we ask you beforehand. So nothing happens to your piece without your knowing about it first.
My piece of jewellery has no stamp. Can it still be tested?
Yes, and that is exactly why we measure. A great deal of old and foreign work was never stamped at all, and the fineness exists quite independently of the stamp. We establish that fineness at the table, with you watching, and the offer is based on what we measure.
Can I test gold at home with a magnet?
You can rule out iron-bearing fakes with it. No more than that: copper and brass are not magnetic either, and plated they look exactly the same. So a magnet tells you what something is not, never what it is.
What is the risk with tungsten?
Tungsten has almost the same density as gold and is therefore used in counterfeit bars. With bars from 100 grams upwards we consequently also carry out an ultrasonic or transmission measurement, because the density test on its own cannot settle the question there.
Does testing cost money?
No. Valuation including all measurements is free of charge and without obligation, even if you do not sell afterwards. You are under no pressure to accept either: you hear the measured fineness, take the piece back and think it over.
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