Read the stamp first
The fastest honest clue is the mark inside a ring, on a clasp, or beside a catch. Look for a karat (10K, 14K, 18K, 22K, 24K), a British carat (9ct, 18ct, 22ct), or a fineness (333, 375, 417, 585, 750, 916, 999). The gold purity chart matches those numbers to a percent.
Read the whole stamp, not the first number. “14K GF”, “1/20 12K GF”, “14KP”, “HGE” and “RGP” are telling you the gold is a layer. People crop the photo on the 14K and skip the GF. The GF is the sentence. The 14K is only describing the layer.
A missing stamp is not a verdict. Small charms, very old pieces, some dental alloy and metal that has been sized can lack a readable mark. A present stamp is not a verdict either. Stamps are punched by machines and by people, and both can lie. Use the mark to choose the next test, not to set the price of a valuable piece by itself.
Hallmarks from an assay office add a second voice: the office, not only the maker, says the fineness. A UK piece may show 375 or 750 plus a sponsor and an office mark. An Indian piece under the BIS scheme is built around a fineness such as 916 and a HUID code. Those systems have changed their exact layouts. A clear fineness mark is still the part you can use today. A fuzzy lion or a worn letter is a reason to ask a jeweler, not a reason to invent a karat.
Safe checks at home
Home checks are good at throwing things out. They are bad at proving a karat. None of them belongs in a listing as “tested, guaranteed 18K.” Do them in this spirit: if the piece fails a safe check, pause. If it passes, you have not finished.
Magnet
Gold is not ferromagnetic. A strong magnet that snaps onto a chain is feeling steel or another magnetic metal. Check the clasp and the posts separately from the links. Costume jewelry often has a steel pin. A gold chain with a steel clasp is a mixed object, not a fake chain. A piece that does not stick can be brass, bronze or thick plate. The magnet never names a karat.
Weight and size
Gold is dense. A solid bracelet has a heft that hollow costume pieces and thin plate often lack. Heft is a feeling, and feelings get fooled by tungsten, by thick plate over a dense core, and by hollow 14K that is honestly light. If you have a scale, write the grams down for later. Do not convert heft into a karat.
Colour and skin
Real gold stays gold-coloured at a scratch only if you have scratched through to gold. Plated pieces show a different metal when the coat fails at a high spot, a clue you can sometimes see on a worn edge without gouging the piece. Skin reactions and green marks come from copper alloys, cosmetics and sweat. They are not a purity assay. Do not file a groove in a ring to “see the colour inside” if you might sell it as jewelry. You just lowered the jewelry value to find a scrap answer.
Float and density, as an idea
A solid gold piece sinks. So does a rock, a steel bolt and most fakes. Floating in water means the object is hollow or less dense than water, which solid gold is not. Sinking means almost nothing. A proper density test needs an accurate dry weight and an accurate wet weight, a fine scale, and no trapped air in a hollow bead. Done casually in a bowl, it is a science-fair version of heft. It is not how you certify a karat.
Ceramic streak, and why to skip it
Dragging jewelry across unglazed ceramic to read a streak can mark the metal. The colour of the streak is easy to misread under kitchen light, and a plated piece can leave a gold-coloured line from the coat you just scraped off. Leave ceramic tiles out of it. The risk sits in the ranking table below.
Tests that belong with a professional
Jewelers use a touchstone and acid, and they use electronic testers that estimate karat from the surface. Assay labs melt a sample or use X-ray fluorescence, which reads the alloy without dissolving it. These are the tests that can support a number. They are also the tests that go wrong in a kitchen.
Testing acids are corrosive. They are sold in kits with a stone and needles, and the instructions assume you will put a strong acid on metal and then on a plate. That can burn skin, damage eyes, ruin clothing and scar a piece. This guide will not walk through an acid procedure. If you want an acid result, ask a jeweler to do it and to tell you which karat needle the streak matched.
Electronic testers are only as good as the surface they touch. Thick plate can read as gold. A rhodium-plated white band can confuse a cheap probe. A good operator tests more than one spot and knows when the machine is guessing. X-ray fluorescence, in a shop that has it, sees the alloy under a thin plate and is the least destructive of the instrument tests. It still needs a person who can interpret a mixed clasp and a solder joint.
For a large lot, a refiner’s assay is the number the payout should follow. Ask whether the assay is of the melt, not of one polite filing taken from the best-looking link. The selling guide covers what to ask for on the receipt.
Spotting gold-plated and gold-filled
Plate is a coat. Edges, engraving and the back of a setting wear through first, and the metal underneath is often grey, coppery or brassy. A price that was never in the jewelry range, a very light chain with a bright uniform colour, and a stamp that says GP or HGE are the usual trio. Weight per length is low compared with a solid chain of the same size.
Gold-filled looks more convincing because the layer is thicker and the stamp looks “official”: 1/20 12K GF, 1/10 14K GF. It wears longer than plate. It still is not solid. Bend a look at the edge of a worn pendant only with your eyes. If you need a number, use the gold-filled calculator with the fraction on the stamp, and expect a small melt value next to a solid chain of the same grams.
Vermeil is silver with a gold coat. The word is a quality claim about the plate on sterling, not a karat of solid gold. Rolled gold plate is a cousin of gold-filled with a thinner layer. Both can be attractive jewelry. Neither should be piled with 14K links on a scrap scale.
Fakes and stamp tricks
- A karat stamp on the clasp only, with an unstamped chain of a different colour.
- A real 14K tag soldered onto a plated body. Look at whether the tag is a different piece of metal.
- “14K” over a buffed-out “GF”, or a stamp so deep it was added later with a punch set from a hardware drawer.
- Coins and bars with the right words and the wrong weight. Weigh against the mint’s specification before you celebrate.
- Magnetic “gold” that is a steel core with a thick skin. The magnet test is there for this one case.
- White metal called white gold that is unstamped silver or rhodium-plated brass. Ask for a test, not a colour opinion.
None of these tricks is rare, and none of them requires you to damage the piece to notice. The pattern is a mark that is newer, deeper or more isolated than the object it claims to describe.
What to do before you sell
Separate anything with a jewelry reason to live: a clear maker’s mark, matched stones, an intact antique, a coin you have not identified. Scrap is the right door for broken chains and single earrings of ordinary karat. It is the wrong door for a piece you have not looked at.
Get one in-person test before you take a scrap price on a lot you cannot afford to misread. Many jewelers will look at a stamp and run a tester at no charge because they hope to buy. That free look is still useful if you write down the karat they called and then compare two shops. You are not obliged to sell to the person who tested it. You are obliged not to hand over a bag of mixed stamps and accept one blended price you cannot replay.
When the karat is known, the calculation guide and the scrap gold calculator turn weight into a melt estimate. Walk in with that estimate. The tester’s karat and your scale weight are the inputs. The offer should be explainable from them.
Tests ranked by reliability and risk
Reliability here means “how often this gets you to the right yes or no on solid gold.” Risk means damage to the piece, to you, or to the sale. The order is a practical ranking for readers, not a published laboratory standard.
| Test | Reliability | Risk | Where it belongs |
|---|---|---|---|
| Assay or X-ray of the lot | Highest for a sale | Low if the lab is competent. A fire assay consumes a sample. | Refiner or assay office, for weight that justifies it. |
| Jeweler’s electronic tester, several spots | High on solid karat, weaker on thick plate | Low. No acid on the piece if they use a probe only. | Jewelry shop, before you accept a scrap price. |
| Acid and touchstone | High in trained hands | High at home: burns and a marked piece. Lower on a jeweler’s stone. | Jeweler. Not a kitchen. |
| Reading the full stamp | Good clue, easy to fake | None | You, first, with a magnifier. |
| Magnet on clasp and chain separately | Rules out some steel cores only | None | You, at home. |
| Heft, worn edges, colour | Low. Suggestive. | None if you only look | You, at home. |
| Float test or casual density | Low unless the scale work is careful | Low, and hollow beads trap air | Optional. Do not treat a sink as proof. |
| Ceramic scratch or filing a groove | Low, and easy to misread | High for anything you might sell as jewelry | Skip. A jeweler can test a discreet spot. |
If a test could scar a piece, and you do not yet know whether the piece is ordinary scrap, you do not need that test at the kitchen table. The information is worth less than the damage.
Questions
Does a 14K stamp prove the piece is 14K?
It is evidence, not proof. Honest makers stamp the karat they alloyed. Stamps are also faked, transferred from another piece, or left in place when the item is gold filled. Read the whole mark, including GF or GP, and test anything valuable.
Can I test gold with vinegar, bleach or acid at home?
Do not pour household chemicals or testing acids on jewelry at home. Acids burn skin and can ruin a piece you might have sold as jewelry. Jewelers and assay offices use acid and electronic testers with training and ventilation. Take the piece to them for the final word.
If a magnet grabs it, is it fake?
A strong pull means a magnetic metal is in the object, often steel in a clasp, post or spring. Solid gold is not magnetic. A magnetic clasp does not prove the chain is fake, and a piece that ignores the magnet can still be plated brass.
Will real gold turn my skin green?
Skin colour is a weak clue. Alloy metals in low-karat gold can mark skin, and so can lotions and plated costume jewelry. A green finger does not prove a fake. A clean finger does not prove 18K.
What is the difference between gold filled and gold plated?
Gold filled is a layer of karat gold bonded to a base, with a weight fraction such as 1/20. Gold plated is a very thin coat. Filled items can have a small melt value. Plated items usually do not. Neither is solid karat.
Should I scratch my ring on ceramic to see the streak?
That test can leave a mark on the metal and tells you little if you do not know what colour you are looking for. Skip it on anything you might keep or sell as jewelry. A jeweler can test a discreet spot.
Who should do the test before I sell?
A jeweler with an electronic tester or an acid stone, or an assay service if the lot is large. Ask what karat they assigned and whether they tested the clasp separately. For a piece that might be antique, get that opinion before you scrap it.
Are coins that look like gold always the gold weight printed on them?
A bullion coin’s face and its gold content are different ideas. Use the actual gold weight from the mint, not the souvenir weight of a plated copy. The coin calculator on this site is for known bullion and pre-1933 US coins, and collector value can exceed melt.
This is a melt-value estimate, not an appraisal or an offer.