Protection from fraud
How to tell real gold: hallmarks, tests and certificates
From reading a hallmark to the magnet, ceramic, density, acid and XRF tests, from checking a bar's sealed pack and certificate to spotting plated jewellery and filled bars. A practical guide for the shop counter and for anyone buying bullion, in person or online.
How to tell real gold
Gold fraud is as old as gold: plated pieces sold as 18K, 14K stamped 22K, fake bars with the right weight and a core of another metal. The good news is that most of these tricks are exposed by simple means in the shop or at home, and that a few rules protect you from almost all of them. This guide orders the methods from the easiest to the most precise, and gives bars a section of their own.
Rule one: the source before the test
The best test is the one you never need: buy from a licensed shop with a name, an address and an invoice, and from an accredited refiner for bars. Most fraud starts with an offer "below the market" from a passing seller or an online advertisement. Raw gold costs the same everywhere in the world at the same moment ($98.19 for a gram of 18K today, November 7, 2026); whoever sells below it is selling something else.
Read the hallmark
Every piece of jewellery should carry its fineness in parts per thousand (750 for 18K, 585 for 14K, 916 for 22K, 375 for 9ct) with the mark of the body that tested it and the maker's mark. What to look for:
- Clarity and depth of the strike; forged marks are shallow or distorted.
- Consistency between the stamped number, the karat on the invoice and the price you were charged.
- The assay mark: in the UK the Assay Office symbol (leopard's head, anchor, rose, castle) with the sponsor's mark and date letter; in India the BIS logo and the six-character HUID, which the BIS Care app can verify; in Egypt the government stamp; in Kuwait and Bahrain the state hallmark.
- Watch for misleading marks: "GP", "GF", "HGE" and "RGP" mean plated or filled, not solid gold; "925" means silver, possibly gold-plated (vermeil); "1/20 12K GF" means a thin layer of 12K on base metal.
A hallmark is strong evidence but can be forged; hence the tests.
Simple tests at home or in the shop
- Magnet: gold is not magnetic. A piece that is strongly attracted is not gold (or has an iron core). But not being attracted proves nothing on its own; copper and silver are not magnetic either.
- Unglazed ceramic: draw the piece gently across an unglazed ceramic tile; gold leaves a gold streak, a fake leaves a black one. It scratches the piece slightly.
- Colour at the wear points: plating wears off at ring edges, inner surfaces and friction points, showing the base metal's colour.
- Density: pure gold has a density of 19.3 g/cm³, 22K about 17.7, 18K about 15.5, 14K about 13.5. Weigh the piece in air, then suspended in water on a thin thread, and divide the air weight by the difference between the two; a figure far below the expected one means fraud. It works for bars and solid pieces, not hollow or stone-set ones.
- Sound: genuine gold coins give a long, clear ring when tapped; fakes sound dull. An approximate test.
Tests at the shop
- Touchstone and acid: a streak of the piece is drawn on a black stone and acid for each karat is applied; if the streak dissolves, the karat is lower than claimed. Old, reliable, slightly scratches the piece and reads the surface only.
- XRF analyser: reads the composition of the surface in percentages in seconds without scratching; available in many jewellers and dealers. Excellent for jewellery, detects thin plating, but cannot see into the core of a thick bar.
- Ultrasound and electrical conductivity for large bars: detect a filled core (tungsten has a density close to gold's but different conductivity and sound).
Ask for a test before paying any large sum; a shop that refuses to test in front of you is a shop to leave.
Bars: a special check
- The sealed pack: small bars come in a heat-sealed assay card; an opened, resealed or scratched pack is a warning.
- The serial number engraved on the bar matches the number printed on the certificate, and some refiners let you verify the number on their website.
- Weight on a precise scale: 10.00 grams, not 9.9; and the dimensions (length, width, thickness) match the refiner's published specifications; a bar with the right weight and larger dimensions contains a lighter metal.
- The refiner's name: on the LBMA Good Delivery list or the Dubai Good Delivery list; bars of unknown origin are bought at a large discount or refused.
- The price: a bar offered with no premium or below the raw price is almost certainly fake.
Plated, filled and vermeil
- Gold plated: a very thin layer of gold over copper or silver; wears off with use and has negligible gold value.
- Gold filled: a thicker layer bonded under pressure; sturdier than plating but not solid gold and not bought as gold.
- Vermeil: sterling silver plated with gold; its value is the silver's.
These are sold legally under their names; the fraud is selling them as karat gold. The hallmark and the fineness number are the dividing line.
Buying online: warning signs
Sponsored advertisements and anonymous shops are the main source of fraud today. Signs that should stop you: a price below the world raw price, "bars" bearing the names of known refiners without a serial number or certificate, photographs copied from other sites, a seller with no address or company registration, insistence on an advance transfer to a personal account, and phrases like "Dubai gold", "Thai gold" or "18K gold plated" that mean the item is not gold. Buy from the official site of a known company or a shop with a branch you can visit, pay by a refundable method, and weigh and inspect the parcel before you sign for it.
Before you pay: a quick checklist
- A licensed shop and an invoice in its name with weight, karat and making charge.
- A clear hallmark matching the invoice.
- Weighed in front of you on the shop's scale.
- An XRF test for large sums, an acid test when in doubt.
- For bars: sealed pack, matching serial number, accredited refiner, sensible price.
Frequently asked questions
Is the magnet test enough?
No; it catches iron-based fakes only. Plated copper and silver are not magnetic either, so combine it with the hallmark and the weight or the acid test.
What do GP or GF on a piece mean?
GP is gold plated and GF is gold filled; neither is solid gold and neither is bought at the gold price.
Can a hallmark be forged?
Yes, so pair the hallmark with a weight, acid or XRF test and with buying from a trusted source.
How do I check a bar I bought years ago?
Compare its weight and dimensions with the refiner's specifications, verify the serial number, and ask any bullion dealer for an XRF or ultrasound test.