How We Test Gold
Last updated
A stamp on a piece of jewelry is a good clue, but it is not proof. Stamps can be faked, worn off, or simply wrong. That is why real gold buyers test every piece, and why you should always watch it happen. Here are the three methods used, in plain language.
1. The acid test
The oldest and most trusted method. A tiny scratch of the piece is rubbed onto a testing stone, and acids of known strengths are applied to the mark.
Real gold of a given karat reacts to those acids in a predictable way. If the mark stays put under an acid meant for 14K, the piece is at least 14K. If it dissolves, it is lower. It is quick, reliable, and jewelers have trusted it for generations.
2. XRF analysis
The modern approach. XRF stands for X-ray fluorescence. The piece is placed in or under a scanner that reads the exact makeup of the metal, gold, silver, copper, and everything else, without cutting, scratching, or harming it at all.
XRF is precise and completely non-destructive, which makes it especially useful for delicate, antique, or high-value pieces where you do not want a single mark left behind.
3. Electronic testers
A handheld device touched to the metal measures its electrical conductivity, since gold conducts differently than the metals used to imitate it. Electronic testers give a fast reading and are a good first check, often used alongside acid or XRF for confirmation.
Why more than one method matters
No single test is the whole story. A skilled buyer often combines methods, a quick electronic reading, an acid confirmation, XRF for the exact content, to be certain. Plating is a good example: a gold-plated piece can fool a surface check but reveals itself once you test past the thin outer layer.
This is where experience earns its keep. After decades of buying gold, our team has seen every kind of piece, every stamp, and every attempt at a fake. We test carefully, and we do it at the counter where you can watch, because the point is for you to trust the result as much as we do.
What this means for you
When you bring gold to Coin Mart, you never have to take our word for it. You see the test, you see the karat confirmed, and only then do we talk about value. See how gold is priced →
Not sure what the stamp on your piece means? Read our full guide to gold karats →
Frequently Asked Questions
- Does testing damage my gold?
- XRF does not touch or mark the piece at all. An acid test uses a tiny scratch on a stone, not on the visible surface of your jewelry. For delicate pieces, non-destructive methods are used.
- Can you test gold with a stamp already on it?
- Yes, and we do, because stamps can be inaccurate or faked. Testing confirms what the stamp claims.
- How long does testing take?
- Usually just a few minutes. You watch the whole thing at the counter.
- Can plated gold pass a test?
- A surface check might be fooled by plating, but proper testing sees past the thin outer layer to the base metal underneath, which is exactly why we test thoroughly.
- Do I need to know my karat before I come in?
- No. We confirm it for you as part of the evaluation.
Visit Coin Mart Jewelry
📍 396 E St, Chula Vista, CA · Est. 1959
Bring your gold in and watch it tested and confirmed in front of you. Walk in, no appointment needed.