How a karatmeter reading is taken, step by step

Before any price gets discussed, your gold has to be read. The machine that does this is called a karatmeter, and most first-time sellers have never seen one work. Here is what actually happens when your jewellery goes under it, step by step, so you know what you are watching.

What the karatmeter measures

A karatmeter is an XRF (X-ray fluorescence) device. It sends a low-level X-ray beam at the surface of your gold for a few seconds and reads the signal that bounces back. Different metals in the alloy — gold, copper, silver, zinc — send back different signatures. The machine's software adds these up and reports a purity percentage, which converts to a karat value: 99.9 for 24k, around 91.6 for 22k, around 75 for 18k, and so on.

This is the same basic technology used in jewellery testing labs across India. It is not a secret formula and not a guess. The number on the screen comes from physics, not from the person standing next to it.

If you have read our post on what the 916 stamp means, you already know that hallmark stamps tell you what a manufacturer claimed at the time of making. A karatmeter tells you what the metal actually is, today, on this piece, right now. That is why the reading matters even on jewellery that already carries a stamp.

Why the test does not damage your jewellery

This is usually the first worry people have, and it is a fair one. Purana sona often carries sentimental weight, not just melting value.

A few things to know about how the test is done:

• No cutting, filing, or scratching. The older acid-and-touchstone method involves rubbing your gold on a stone and applying acid to the mark. A karatmeter needs none of that.
• No melting. The piece is tested exactly as it is, chain, ring, or bangle, without altering its shape.
• The X-ray only reads the surface. The beam does not pass through the item or change its structure.
• The piece stays in view. It sits on or near the machine while the reading is taken. You do not need to hand it over and wait in another room.

Because nothing is cut or dissolved, the same piece can be tested more than once if you want a second reading before you decide anything.

What the reading actually shows, and what it does not

The karatmeter gives you a purity number for the metal it scanned. A few limits are worth knowing so the number is not misread:

• It reads the spot it scans. Gold plating over a base metal, or a piece with mixed layers, can give a different reading depending on exactly where the beam lands. This is one reason a shop may test more than one point on a larger piece.
• It does not weigh your gold. Purity and weight are two separate steps. The karat reading tells you what percentage of the metal is gold; a separate weighing on a calibrated scale, in front of you, tells you how much of it there is.
• It does not set the price by itself. The karat percentage and the weight are combined with the day's gold rate to reach a payout figure. If you want to understand why that payout is lower than the rate you see in the news, our post on why the published rate is not your payout walks through that separately, so we won't repeat it here.

If a piece has stones set into it, the reading applies to the gold only. The shop does not test, value, or buy the stones themselves, only the metal around them.

What to watch for while it happens

You do not need any technical knowledge to follow this test. You just need to watch the same three things every time:

1. Your item stays visible. It should not be carried out of sight before or during the test.
2. The screen is readable from where you stand. The karat percentage should show clearly, and you should be able to ask what it means before moving to the next step.
3. The sequence is: test, then weigh, then calculate. If someone quotes you a final cash number before either step has happened in front of you, ask to see the reading first.

It is also fine to ask for the test to be repeated, or done at a second point on the same piece, especially on something heavier like a kada or a mixed-karat set. A non-destructive test costs nothing to redo.

Once the karat and weight are both established, what happens next — the math, the deductions, and how the cash is handed over — is covered in what happens between the counter and the cash. And if you are still gathering what to bring with you, our post on what to bring when you sell gold covers that groundwork.

The short version

A karatmeter reads your gold's purity using an X-ray beam, in seconds, on the surface only, without cutting or melting anything. It is one input, alongside weight, into the final number. You are meant to see all of it: the item on the machine, the percentage on the screen, and the weight on the scale, in that order, before any cash figure is discussed.

How the karatmeter reading is taken · Why the published rate is not your payout · What happens between the counter and the cash ·

Questions people ask

Does a karatmeter test damage jewellery? No. It is an X-ray fluorescence reading taken from the surface; nothing is scratched, cut or melted, and the piece is handed back exactly as it came.

How long does a karatmeter reading take? Under a minute per piece once it is on the plate. You watch the screen while the reading is taken, which is the point of using the machine.

Can I see the reading myself? Yes, and you should insist on it anywhere you sell. At our counter in Greater Noida West the screen faces you. Call 9217742656 if you want to ask about a specific piece first.

What 916 means on your jewellery