Is gold magnetic? The magnet test, hallmarks and what scrap gold is worth
Gold is not magnetic. It is one of the few metals that a magnet faintly pushes away rather than pulls towards it, so if a magnet sticks to a ring, a chain or a coin, the item is not solid gold. The reverse is not true: copper, brass, silver and aluminium ignore a magnet just as gold does, which is why the magnet is only the first of several tests.
Gold and magnets: key facts
| Is gold magnetic | No. Gold is diamagnetic: a strong magnet repels it very slightly, and no magnet attracts it |
|---|---|
| If a magnet sticks | The item is plated or filled over a base metal such as steel or nickel, or the magnet has found a steel spring in the clasp |
| If a magnet does not stick | The item might be gold, or copper, brass, bronze, silver, aluminium or a non magnetic plated alloy. The magnet rules things out, not in |
| The carats | 9ct is 375 parts gold in 1,000, 14ct is 585, 18ct is 750, 22ct is 916 and pure gold is 999. The rest is copper, silver, zinc, palladium or nickel |
| The hallmark | UK law requires gold over one gram sold as gold to carry a hallmark struck by an assay office: the maker's mark, the fineness number and the office mark |
| The density | Pure gold weighs 19.3 grams per cubic centimetre, 18ct roughly 15 to 16, 9ct roughly 11. Few other metals come close |
Why gold ignores a magnet
The magnetism you can feel, the kind that holds a note to a fridge, belongs to iron, nickel and cobalt, whose atoms line up their magnetic moments together. Gold's electrons are arranged so that it does the opposite in a tiny way: placed in a strong magnetic field, it is repelled by an amount far too small to notice without a laboratory. This is called diamagnetism, and gold shares it with copper, silver, lead and zinc. So a hand magnet, however strong, does nothing to solid gold of any carat.
What a sticking magnet tells you
If a magnet grabs the piece, there is iron, nickel or cobalt in it, and that means it is not solid gold. The usual explanations are gold plating or gold filling over a steel or nickel base, a cheap alloy sold with an impressive colour, or a clasp whose spring is steel while the rest of the chain is fine. Test the body of the piece away from the clasp before you condemn a whole necklace. Many plated items are made over brass or copper rather than steel, so plenty of fakes pass the magnet, which brings us to the harder half of the question.
What a non magnetic result does not tell you
Passing the magnet test means only that the item is not built on iron, nickel or cobalt. Brass, which is yellow, heavy and common in costume jewellery, passes. So do bronze, copper and silver, and so does tungsten, which has nearly the same density as gold and has been used in the cores of fake bars. White gold is a gold alloy with palladium or nickel: the nickel versions are not noticeably magnetic because the nickel is a small share of the alloy, so the magnet does not help you tell white gold from steel plated to look like it. For anything that passes, move to the hallmark and the density.
Reading the hallmark
Under the Hallmarking Act 1973 an article described as gold and weighing more than one gram must be hallmarked by one of the UK assay offices in London, Birmingham, Sheffield or Edinburgh before it is sold. A full hallmark has three compulsory parts: the sponsor's or maker's mark, the fineness number in a shaped shield (375, 585, 750, 916 or 999), and the mark of the assay office, which is a leopard's head for London, an anchor for Birmingham, a rose for Sheffield and a castle for Edinburgh. Older pieces carry a crown and a carat figure instead of the fineness number, and a date letter. A hallmark is strong evidence, because the office tests the metal before striking it, but marks can be forged or transplanted from a scrap piece, so a mark on a piece that fails the density check deserves a closer look. Our 9ct gold guide has more on what the mark proves and what it does not.
The density check
Weigh the piece on a scale that reads to a tenth of a gram, then lower it on a thread into a container of water on the same scale and note how much the reading rises: that rise in grams equals the volume in cubic centimetres. Divide the dry weight by the volume. Pure gold gives 19.3, 22ct about 17.7, 18ct between 15 and 16 depending on the alloy, 14ct 13 to 14 and 9ct 10.9 to 12.7. Brass gives around 8.5, silver 10.5, steel about 7.9. Stones, hollow sections and air trapped in a chain throw the result off, so test solid pieces. A buyer with an X ray fluorescence analyser settles the question in seconds, which is why serious buyers rarely rely on acid tests any more.
What scrap gold is worth
Gold is priced from the London Bullion Market Association's daily price per troy ounce. Divide that by 31.1 for the price of a gram of pure gold, multiply by the fineness (0.375 for 9ct, 0.750 for 18ct) and you have the gold content of a gram of your piece. A buyer offers a share of that figure, with jewellers and refiners paying more and high street cash for gold counters paying less. Gold is not scrap metal in the legal sense, so the no cash rule that covers copper and steel does not apply, but the same advice does: get two quotes by weight and carat, and sell to a buyer who tests in front of you. Our guides to 9ct gold scrap prices and scrap silver prices walk through the sums and the buyers.
Frequently asked questions
Is gold magnetic?
No. Gold is diamagnetic, meaning a strong magnet pushes it away very slightly and no magnet attracts it. A hand magnet does nothing to solid gold of any carat.
Why does a magnet stick to my gold ring?
Because it is not solid gold. Either it is gold plated or gold filled over a steel or nickel base, or the magnet has found a steel part such as a clasp spring. Test the body of the piece away from the clasp.
Is white gold magnetic?
No. White gold is gold alloyed with palladium or nickel, and even the nickel versions are not noticeably magnetic because the nickel is a small share of the alloy.
Can a magnet tell if gold is fake?
Only one way round. A magnet that sticks proves the item is not solid gold. A magnet that does not stick proves nothing, because brass, copper, silver and tungsten pass the test too. Check the hallmark and the density as well.
How do I test gold at home?
Use the magnet first, then read the hallmark for the fineness number and assay office mark, then do the density check with a scale and a glass of water: pure gold is 19.3 grams per cubic centimetre, 18ct about 15 to 16, 9ct about 11.
Is gold plated jewellery worth anything as scrap?
Almost nothing. The gold layer is a few thousandths of a millimetre thick, and recovering it costs more than it is worth. Buyers pay for solid gold by weight and carat.