Before you take any piece of gold to a buyer, you want to know one thing: is it actually gold? Lots of items look like gold, weigh like gold, even sound like gold but are brass, pyrite, or gold-plated base metal. The wrong answer at the pawn counter can cost you hundreds of dollars or embarrassment in front of the appraiser. Five home tests, run in the next ten minutes, will tell you with reasonable confidence whether what you have is the real thing.
None of these tests are perfect. The only definitive proof is a professional acid or electronic test at a jeweler (often free, takes 30 seconds). But the home tests below will catch obvious fakes, build your confidence, and tell you which pieces are worth carrying to a buyer in the first place.
Try this first: the magnet test
Real gold is not magnetic. Most cheap counterfeits use iron or steel cores plated with gold. This single test rules out the majority of fakes in five seconds with zero tools beyond a fridge magnet.
Important limitation: the magnet test only catches MAGNETIC fakes. Brass, copper, lead, and most cheap non-magnetic alloys will also pass this test. Passing means MIGHT be gold, not DEFINITELY gold. For anything worth more than $200, run at least Tests 2 and 4 below before selling.
Start here: look for a hallmark stamp
This is not technically a test. It is a quick triage that rules out most fakes before you do anything else.
Look on the inside of a ring band, the clasp of a necklace, or the back of an earring or pendant. Real gold jewelry sold legally in the United States is almost always stamped with a karat mark. Common marks are 375 (9k), 417 (10k), 585 (14k), 750 (18k), 916 (22k), and 999 (24k pure). You may also see literal “14K” or “18K” instead of the three-digit version.
If you find a stamp, write down what it says. The karat number is what you will plug into the calculator later to estimate value. If you find nothing, move on to the tests below.
Test 1: The magnet test
Rules out iron-core fakes in 5 seconds. Real gold is not attracted to a magnet. Iron, steel, and many cheap base-metal alloys used in counterfeits are. A small magnet, like the kind on the back of a refrigerator letter or souvenir, is enough.
Hold the magnet close to your piece, almost touching it. If the piece jumps toward the magnet or sticks to it, you are not looking at gold. Most likely it is steel or iron with a gold-color coating.
Test 2: The vinegar test
Household white vinegar is dilute acetic acid, around 5% strength. Real gold is unreactive with weak acids like vinegar. Base metals like brass, copper, and silver-plated alloys will discolor, fizz lightly, or leave a residue on a cotton swab.
Put a drop or two of vinegar on an inconspicuous spot of your piece. Let it sit for 15 minutes. Wipe with a clean cloth or cotton swab.
If the spot is unchanged, that is a positive sign. If you see green tinting (copper reacting), darkening, or a tarnish ring, the piece is not solid gold. It may be gold-plated brass or a similar alloy.
Test 3: The ceramic scratch test
Real gold leaves a gold streak on unglazed ceramic. Pyrite (fool’s gold) leaves a greenish-black streak. Gold-plated base metals usually leave a streak that does not match the color of the surface, because the plating wears off and the base metal shows through.
Find a piece of unglazed ceramic. The unfinished back of a bathroom or kitchen tile is usually unglazed and works well. A new piece costs about a dollar at any tile shop.
Drag a corner of your gold piece across the ceramic with firm pressure. Examine the streak left behind. Real gold leaves a yellow-gold color that matches the piece. Fool’s gold leaves blackish-green. A streak that starts gold and then turns silvery as you keep dragging tells you the piece is plated.
Test 4: The density (water displacement) test
This is the gold standard of home tests. Gold is one of the densest common metals, at 19.3 grams per cubic centimeter for pure 24k. Most fakes are much less dense, because the base metals used (brass at 8.5, lead at 11.3, tungsten as a fake at 19.25 is the rare exception) do not match gold’s specific density.
You need a small kitchen scale that reads to 0.1 grams, a graduated cylinder or measuring cup that reads in milliliters, water, and a piece of string. Any standard kitchen scale in the $10 to $20 range will work.
- Weigh your piece dry. Write down the grams.
- Fill the cylinder with water. Enough to fully submerge your piece. Note the starting water level in milliliters.
- Submerge the piece. Tie the string to your piece and lower it into the water until fully submerged but not touching the bottom or sides. Note the new water level. The difference in milliliters is the volume of your piece in cubic centimeters (1 ml = 1 cm³).
- Compute density. Divide the dry weight in grams by the volume in cubic centimeters. The result is the density.
If your density is close to one of the gold benchmarks (within 0.5 grams per cubic centimeter), the piece is likely solid gold of that karat. If your density is far below 11, you are probably looking at brass or another base metal.
Test 5: The nitric acid test
Professional jewelers use nitric acid kits to confirm gold karat. The principle is simple: nitric acid eats most base metals but does not touch gold. The reaction tells you exactly what you have.
You can buy a basic kit online for $15 to $30. It usually comes with several acid bottles, one for each karat range (10k, 14k, 18k, 22k), a small testing stone, and instructions.
You drag a small scratch of your piece across the testing stone, then drop one acid on it. If the streak dissolves, the piece is below that karat. If it remains, it is at or above. By testing with multiple acids, you narrow down the exact karat.
For most people, this test is overkill. A free 30-second test at any jeweler will give you the same answer with zero risk. The acid kit is worth it only if you are checking many pieces and want to do it yourself.
When home tests are not enough
Home tests catch obvious fakes. They do not catch sophisticated counterfeits, partial gold (like a heavy 14k chain with a 10k clasp soldered on), or pieces with hidden non-gold cores.
Take a piece to a jeweler for a free professional test in any of these cases:
- You inherited the piece and have no idea what it is
- Your home tests give mixed results (passes magnet, fails vinegar)
- The piece is worth more than $500 if real
- You are about to sell it to a buyer for a meaningful sum
- The piece is a heavy bar or large bullion coin (tungsten core concern)
Most jewelers test for free in 30 seconds with an acid kit or a hand-held electronic tester. Some require an appointment. Call ahead to confirm. The 10-minute drive will save you from selling a $50 piece for $300 or vice versa.
Frequently asked questions
Can I tell if gold is real without any tools?
Partly. Check for a hallmark stamp and try the magnet test (a fridge magnet works). These two cost nothing and rule out roughly 70% of obvious fakes. For the remaining 30%, you need at least vinegar, ceramic, or a jeweler visit.
Does real gold tarnish or change color?
Pure 24k gold does not tarnish. 14k and 10k gold can develop a slight patina over years because they contain copper and silver in the alloy, but they should not turn green or black quickly. A piece that visibly tarnishes within weeks of normal wear is likely gold-plated, not solid.
What about gold-filled vs gold-plated?
Gold-filled jewelry has a thick layer of gold (at least 5% of the total weight) mechanically bonded to a base metal core. Gold-plated has a much thinner layer applied electrochemically. Both will fail the vinegar and ceramic tests over time as the gold layer wears down. Gold-filled often passes the magnet test but fails density (because the core is brass or steel).
Is the bite test reliable?
No. The bite test (biting a coin to see if it dents) worked when gold coins were softer than human teeth and counterfeits were harder. Modern fakes can be soft on purpose, and biting risks chipping a tooth. Skip it.
Should I trust an online video that says my gold is real?
Not for anything valuable. Photos and videos cannot show density, hallmark detail at close range, or response to acid. Treat online opinions as entertainment, not appraisal. For any piece worth over $100, the only reliable confirmation is a physical test, ideally at a jeweler.