Collectors
- Start with the hallmark. 10K, 14K, 18K, or 417, 585, 750 - and learn the marks that mean it is not solid gold: GP, GF, HGE, EP.
- Gold is not magnetic. A magnet can rule a piece out quickly, but a non-magnetic piece is not thereby gold.
- Density is the best home test - gold is extraordinarily heavy, about 19.3 grams per cubic centimetre.
- An XRF scan at a jeweller is the practical answer - non-destructive, a minute's work, and often done free. Pair it with a weight check, because XRF reads the surface.
Read the Marks First
Most real gold jewelry carries a stamp, usually inside a ring shank, on a clasp, on the back of a pendant, or on an earring post. Worth knowing for US buyers: unlike the United Kingdom, the United States has no compulsory hallmarking - marking is voluntary, and the law governs only whether an applied mark is accurate. It is small - a loupe or a phone camera at maximum zoom is often needed. The marks you want are 10K, 14K, 18K, 22K, 24K or their parts-per-thousand equivalents 417, 585, 750, 916, 999.
Just as important are the marks that tell you it is not solid gold. GP is gold plated. GF is gold filled, often written as a fraction such as 1/20 12K GF. HGE is heavy gold electroplate. EP is electroplate. Vermeil means a gold layer over sterling silver. Any of these means a layer rather than solid metal, and our vermeil explainer covers how thin those layers actually are.
Two honest caveats. A hallmark can be faked - stamps are easy to apply and counterfeiters apply them. And the absence of a hallmark does not prove a piece is fake, since marks wear away over decades and some older or handmade pieces never carried one. So the stamp starts the investigation; it does not finish it.
Non-Destructive Checks Worth Doing
The magnet test. Gold is not magnetic. Hold a strong magnet - a rare-earth magnet, not a fridge magnet - near the piece. If it is attracted, there is a ferrous metal in there and it is not solid gold. Two limits: clasps, springs, and pins are often steel on otherwise genuine pieces, so test the body rather than the fittings; and many counterfeits use non-magnetic base metals, so passing this test means very little.
Weight in the hand. Gold is remarkably dense - about 19.3 grams per cubic centimetre, roughly two and a half times steel. Real gold feels startlingly heavy for its size, and this is the check experienced buyers rely on most. It is subjective until you have handled enough of it, and then it becomes quite reliable.
The density test makes that objective. Weigh the piece on a jeweller's scale, then measure the water it displaces, and divide mass by volume. A result near 19.3 suggests high-purity gold; 14k alloys land around thirteen to fifteen depending on composition, so the test tells you which karat range you are in rather than simply real or fake. The famous blind spot is tungsten, whose density is almost identical to pure gold - but note the limit of that concern: tungsten cannot be cast or worked like gold, so tungsten substitution is overwhelmingly a bullion-bar problem, and a tungsten core would read far too heavy for a piece stamped 585.
Look at the wear points. On a plated piece, edges, high spots, and the inside of a ring shank wear first, and a different colour showing through under magnification is conclusive. Check where a chain rubs and where a ring meets the finger.
Tests That Damage the Piece
The acid test works and it is destructive. It involves rubbing the piece on a testing stone and applying graded acid solutions to see which dissolves the mark. Nitric acid alone only discriminates at the low end; the reagents for 14k and 18k add hydrochloric acid, and above 18k the mixture is aqua regia. Jewellers use the method routinely and it is accurate on solid metal - but it leaves a mark, it can be defeated by thick plating, and the reagents are genuinely hazardous. This is not a kitchen-table activity.
The ceramic scratch test - dragging the piece across unglazed ceramic to see whether it leaves a gold streak or a black one - is often described as harmless. It is not: it abrades the surface, and on a plated piece it removes the plating exactly where you tested. Use it on scrap, not on jewelry.
The bite test belongs to films. Gold is soft enough to mark, but so are several base metals and platings, and you will damage a piece and your enamel for a result that means nothing.
Vinegar, bleach, and toothpaste tests circulate widely and are a poor idea. They are unreliable indicators, and chlorine in particular attacks the alloy metals in karat gold - our cleaning guide explains why chlorine can crack gold rather than merely dull it. Deliberately applying bleach to jewelry to test it risks doing real harm to a piece that turns out to be genuine.
The Answer That Actually Settles It
Take it to a jeweller with an XRF analyser. X-ray fluorescence reads the elemental composition of the metal without marking it, gives you the karat and often the full alloy breakdown, and takes about a minute. Many jewellers and most gold buyers have one, and a good number will scan a piece at no charge - though it is not universal, and free testing from someone hoping to buy the piece is a service with an interest attached.
Understand one limitation so you are not misled: XRF reads the surface and a small depth beneath it, so a thickly plated piece can return a gold reading. A jeweller who knows their instrument will check an edge or a worn area, or combine the scan with a weight check, precisely because of this.
Be careful about the other electronic option, because the category is not one thing. The common pen-style electronic gold testers work electrochemically at the surface and are more easily fooled by heavy plating than XRF is - they are not a deeper check. What does read through a coating is a bulk-resistivity or eddy-current verifier, the instrument type sold specifically to catch plated and tungsten-cored fakes. If a piece matters and plating is the worry, ask whether the shop has one of those rather than assuming any electronic tester will do. Between an XRF scan, a resistivity check, and a weight, an experienced jeweller can settle almost any piece in a few minutes.
For anything of real value - an inheritance, an auction purchase, an insurance appraisal - this is the route. Home tests are for triage: they let you discard the obvious fakes and identify what deserves a professional look. Our 14k versus 18k guide covers what the karat you find actually means, and the 925 explainer does the same for silver, where the fakes are different and the vocabulary is its own trap.
Buying Without Getting Caught
Most people asking this question are about to buy something rather than test an heirloom, and prevention is easier than diagnosis. Buy from sellers who state the karat in the listing, publish a weight in grams, and answer a direct question about the alloy. Weight is the single most telling specification, and the sellers least willing to publish it are the ones you should be most careful with.
Be alert to the vocabulary of evasion. Gold tone, gold finish, gold colour, gold overlay and 18k gold plated all describe things that are not solid gold, and all appear in listings designed to be skim-read as though they were. The word to look for is the karat mark with nothing qualifying it.
And weigh the price against the metal. Gold has a public market price, so an informed seller is very unlikely to offer a solid gold piece far below the value of the gold in it. Treat a heavy chain priced at a fraction of its stated weight in gold as a strong signal to test rather than as a bargain - though not as proof, since estate, pawn, and thrift sellers genuinely do price below melt when they have not weighed or tested the piece themselves. The price tells you where to look, not what the answer is.
Frequently Asked Questions
Does a magnet stick to real gold?
No. Gold is not magnetic, so attraction to a strong magnet rules a piece out. The reverse is not true: many fake pieces use non-magnetic base metals, and clasps and springs on genuine pieces are often steel. Test the body of the item, not the fittings, and treat a pass as inconclusive.
What do the numbers 585 and 750 mean on jewelry?
They state gold content in parts per thousand, as a guaranteed minimum. 585 corresponds to 14k, which is 58.33 percent gold; 750 is 18k, exactly 75 percent. You may also see 417 for 10k, 916 for 22k, and 999 for pure gold. These marks are the fastest indication of what a piece claims to be - though in the US, marking is voluntary and its absence proves nothing.
Can you tell if gold is real by its weight?
Often, and it is the most useful home check. Pure gold is about 19.3 grams per cubic centimetre - roughly two and a half times as dense as steel - so real gold feels surprisingly heavy for its size. Karat alloys are lighter, with 14k around thirteen to fifteen. The famous caveat is tungsten, whose density nearly matches pure gold, but that is mainly a bullion-bar problem: tungsten cannot be cast into jewelry the way gold can.
Is the acid test safe for jewelry?
No, it is destructive. It requires rubbing the piece on a stone to leave a metal trace and applying graded acid reagents - nitric for low karats, nitric with hydrochloric for 14k and 18k, aqua regia above that. It leaves a mark. Jewellers use it because they know where to place that mark so it will not show. It is not a home test, and the reagents are genuinely hazardous.
What does GP, GF, and HGE mean on jewelry?
They all mean a gold layer rather than solid gold. GP is gold plated, GF is gold filled - a thicker bonded layer, often written as a weight fraction like 1/20 12K GF - and HGE is heavy gold electroplate. Seeing any of these is a clear statement that the piece is not solid gold.
How can I get gold tested for free?
Take it to a jeweller or a gold buyer with an XRF analyser. The scan is non-destructive, takes about a minute, and gives the karat and often the full alloy composition. Many will do it at no charge, particularly buyers - which is worth remembering, since they have an interest in the outcome. Ask them to test a worn edge as well as a flat face, since XRF reads the surface and heavy plating can mislead it, and ask whether they can also put it on a resistivity verifier if plating is your concern.
Does real gold tarnish or change colour?
Solid gold does not tarnish. Lower-karat gold can darken very slightly at the surface because of the copper and silver in the alloy, and any gold can look dull from soap film and skin oil. Obvious colour change, or a different metal showing at the edges, points to plating wearing through.
Related Guides
How We Research
Our guides draw on manufacturer documentation, established industry practice, and what we learn testing and researching products for our buying guides. Where practice varies or opinion divides, we say so rather than pretending at consensus.
Selling note: If you are having gold tested before selling it, get it scanned at two places rather than one, and ask each for the karat reading rather than only the offer. A buyer who will not tell you what the metal tested at is not a buyer you want, and the reading is a fact you are entitled to before any price is discussed.