How to tell if gold is real at home

You have a drawer of old chains, a ring from a relative you never met, or a dental bridge you saved because it felt too heavy to throw away. Before you calculate what it is worth, you need to know how to tell if gold is real. A piece that looks solid can be plated, filled, or simply a base metal with a yellow wash. The answer is not a single test: it is a sequence that starts with your eyes and ends with a drop of acid. Each step is described below, in the order you should do them, so you can walk into a buyer knowing what your piece is and roughly what it is worth.

You are not testing for fun. You are testing because the price of a gram of 14K gold is several times the price of a gram of brass. A stamp that says '14K' is not proof of anything. A stamp is a claim, and claims need checking. The good news is that the checking is cheap, fast, and does not require a laboratory. The bad news is that one wrong assumption, like thinking gold-filled is solid, can cost you most of the value you thought you had. Read the stamps first. They tell you which tests are worth doing at all.

Every piece of jewellery made for sale in a regulated market carries a hallmark or a fineness stamp somewhere on it. Look on the inside of a ring band, on the clasp of a necklace or bracelet, and on the back of earrings or pins. You will often need a loupe or a phone camera with a macro lens, because the numbers are small. A stamp like '14K', '585', '750', or '916' tells you the karat. The karat is the single biggest factor in the piece's melt value. But a stamp can also tell you the opposite: that the piece is not solid gold at all.

Three abbreviations matter most: GP (gold plated), GF (gold filled), and HGE (heavy gold electroplate). RGP stands for rolled gold plate, which is the same family as gold filled. The US Federal Trade Commission, under 16 CFR 23.4, requires that a gold-filled item be at least 1/20 of its total weight in gold content by weight, and that the gold layer be at least 10K. A stamp like '1/20 14K GF' or '14K GF' means the item is a sandwich: a base metal core with a layer of gold bonded to it. HGE, by contrast, has no minimum thickness beyond what the electroplating process leaves. The gold layer is often a few millionths of an inch thick. If you see GP, GF, HGE, or RGP anywhere, stop thinking of it as solid gold. It is not. It has a melt value, but it is a fraction of what the same weight in solid gold would bring. The buyer's scale will weigh the base metal too.

One more stamp to know is the one that is not there. Plated items are not required to carry a karat stamp at all. A piece with no stamp is a candidate for testing. A piece stamped '14K' with no other mark is still just a claim, but it is a claim you can test.

What the Magnet Catches and What It Misses

Take a strong neodymium magnet, the kind sold as a rare-earth magnet, and hold it against the piece. Gold is not magnetic. If the piece sticks hard to the magnet, it contains a significant amount of iron, nickel, or cobalt. It is not solid gold. That is the magnet test gold sellers use first. It is free, takes two seconds, and catches the most common fakes: brass or steel items with a gold-coloured plating. A chain that snaps to the magnet is a chain you can stop testing. It is worth its weight in base metal, not gold.

But the magnet test has a limit. Many gold alloys that contain no iron are still not attracted to a magnet. A 14K piece alloyed with copper and silver, which is the standard for yellow gold, will not stick. A piece of gold plated over copper or brass will not stick either, because copper and brass are not magnetic. A piece that does not stick to the magnet is not proof of gold. It is only proof of the absence of steel. You still need to know the karat, and the magnet cannot tell you that. Use the magnet test as a quick screen, not as a verdict. Move on to the test that can actually assign a karat number.

How to Read the Acid Reaction

The gold testing kit you buy online or at a jeweller's supply store is a small bottle of nitric acid, or a set of bottles with different strengths, plus a dark stone for rubbing. The principle is simple: you rub the piece on the stone to leave a thin streak of metal, then touch the streak with acid. The acid reacts with the base metals in the alloy. The colour of the reaction tells you the karat. A 10K streak will fizz and turn a milky green. A 14K streak will turn a slower, paler cream. An 18K streak barely reacts. A 22K or higher streak does nothing at all, because the acid is not strong enough to attack it. The kit's chart tells you which colour means what.

Safety Rules You Must Follow

Safety is not optional here. Nitric acid in a typical kit is concentrated, between 10% and 70% depending on the manufacturer. It causes severe chemical burns on contact with skin and permanent damage to eyes. The fumes are toxic and corrosive. Work in a well-ventilated area, ideally outside or under a range hood. Wear nitrile gloves and safety glasses. Keep a box of baking soda nearby. Neutralising a spill with baking soda is the correct first response. Do not pour used acid down the sink. Neutralise it with baking soda first, then rinse it away with plenty of water. The manufacturer's instructions for a nitric-acid gold testing kit, which ship with the bottle, will tell you the exact concentration and disposal requirements for that specific product. Read those instructions before you open the bottle, not after.

The acid test is destructive only to the tiny streak on the stone, not to the piece itself. It does leave a visible mark on the stone. If you are testing a piece you intend to keep, this is fine. If you are testing a piece you intend to sell, do the acid test in front of the buyer or on a spot that will not affect the piece's value. A buyer may run their own test anyway. The kit costs roughly $15 to $30 and lasts for years if you keep the cap tight.

When the acid test is not enough, or when you do not want to damage a piece you might keep, the next step is an electronic tester or an X-ray fluorescence (XRF) analyser. An electronic tester measures electrical conductivity. Gold resists it in a way that is predictable by karat. You touch a probe to the piece, the meter reads the resistance, and a chart converts that to a karat estimate. These machines are cheap, portable, and non-destructive. They can be fooled by plating and by some alloys. They only read the surface. An XRF analyser, by contrast, fires X-rays at the piece and reads the spectrum of fluorescent radiation that comes back. It tells you the exact percentage of gold, silver, copper, and other metals in the top few microns. It can identify a plated piece instantly because it sees the base metal under the gold layer.

XRF machines are not consumer items. They cost thousands of dollars. They are what a serious buyer uses to verify a piece before they quote a price. If you are selling, you do not need to own one, but you should know what it is. A buyer who uses one is a buyer who is not guessing. Ask if the buyer uses XRF. If they do, ask to see the reading for your piece. A buyer who refuses to show the reading, or who quotes a karat that contradicts the XRF result, is a buyer to walk away from. For the seller, the practical role of XRF is as a second opinion. If your acid test says 14K and the buyer's XRF says 10K, believe the XRF. The acid test is only as good as the streak you rubbed and the chart you read.

Here is the reference you will come back to when a stamp is too small to read or too confusing to trust. This table lists the markings that mean the piece is not solid gold, and what each one actually means for the gold content.

Stamp	Full Term	What It Means for Gold Content
GP	Gold plated	A thin gold layer, electroplated onto base metal; no minimum thickness in US law (16 CFR 23.3)
GF	Gold filled	At least 1/20 of total weight is gold content, and the gold layer is at least 10K (16 CFR 23.4)
HGE	Heavy gold electroplate	A gold layer applied by electroplating; no minimum thickness; often thinner than gold filled
RGP	Rolled gold plate	A thin gold layer bonded to base metal; similar to GF but not always meeting the 1/20 minimum
1/20 14K	Fractional gold filled	Means 1/20 of the total weight is 14K gold; the rest is base metal

The table below compares the three tests you are most likely to use at home, plus the two you might meet at a buyer. See at a glance which one answers which question.

Method	What It Detects	Cost	Destructive?	Limits
Magnet test	Iron, nickel, steel content	Free	No	Passes plated brass; cannot assign a karat
Nitric acid kit	Karat by colour reaction	$15–$30	Yes, on the test streak	Needs skill to read colours; acid is hazardous
Electronic tester	Electrical conductivity	$50–$200	No	Surface only; can be fooled by plating
XRF analyser	Exact metal percentages	$3,000+	No	Sees top few microns; buyer-owned

Get a Second Opinion

If you have read the stamps, done the magnet test, and run an acid test, and you still cannot decide whether a piece is solid, you have two honest options. The first is to take it to a local jeweller who does on-site testing and ask for a karat reading. This will cost nothing or a few dollars. A reputable shop will do it while you watch. The second is to find a buyer who uses XRF and let their machine settle it. Do not guess. A guess on karat is a guess on the single largest number in your calculation. A 10-gram piece at 14K is worth about 35% more than the same piece at 10K. The difference between a plated chain and a solid one is not a percentage, it is a factor of ten or more.

The One Thing You Should Not Do

Here is the failure case. It happens at 1am when every shop is shut and you are staring at a chain you found in a drawer. Do not scratch it. Do not bite it. Do not drop acid on it while you are holding it over the sink. Put it in a sealed bag. Write down what you think it is. Wait until a shop is open. Gold is not going anywhere. The spot price will be there in the morning. A night of impatience is how people learn what a piece is not, after they have already damaged it.