The hallmark stamped on your jewelry is not an absolute guarantee of its purity. It can be worn away, mistaken, or simply fake. That is why, before buying a single gram of gold, a professional never relies on the marking alone: they test it.
Do you want to know whether your chain is really 18 karat, or whether that inherited piece is solid gold? The good news is that the purity of gold can be measured precisely, through several complementary methods. Understanding them is how you make sure you never sell — or buy — blind.
At Jayma Or, we check the purity of the gold we buy in Dakar every single day. We test and weigh in front of you, we explain the result, and we pay cash the same day. Here, method by method, is how a gold content is actually verified.
In this article, you will discover:
- what gold purity really means (and why it sets the price);
- the 4 main checking methods, explained simply;
- the advantages and limits of each;
- how we combine these methods for a fair estimate.
Gold purity: the basis of all value
Since pure gold is too soft for jewelry, it is alloyed with other metals. The proportion of gold that remains is the fineness, expressed in karats:
- 24 karat: 99.9% gold (pure gold);
- 21 karat: 87.5% gold;
- 18 karat: 75% gold;
- 14 karat: 58.3% gold.
These percentages are no minor detail: they are the price. The same weight in 21 karat is worth considerably more than in 14 karat, because it contains far more actual gold. To understand the composition, see also the different types of gold alloys. This is exactly why purity must be measured carefully.
Method 1: the hallmark (a clue, not proof)
The first check is visual: look for the hallmark, that small number engraved on the piece (24K, 21K, 18K, 14K, or 999, 875, 750, 585). It indicates the theoretical fineness.
But be careful: the hallmark is a starting point, not a certainty. It can be worn, badly stamped, or fraudulently applied to a lower-quality metal. A plated piece may even carry a misleading mark. It is useful as a guide, never as a conclusion.
Method 2: the acid test (the proven benchmark)
This is the oldest and most widespread method. You rub the piece on a touchstone to leave a trace of metal, then apply an acid calibrated for each fineness. Depending on the reaction — the trace resists or dissolves — you determine the karat.
- Advantages: reliable, fast, inexpensive, proven over centuries.
- Limits: it requires a small trace of metal (a very minimally invasive test), and reading it takes experience. On a thickly plated piece, you have to test beneath the surface.
Done properly, the acid test gives a reliable result in moments — it is the gold buyer's everyday tool.
Method 3: the electronic tester
The electronic tester measures the conductivity of the metal using a probe and displays an estimate of the karat. Fast and clean, it complements the acid test very well.
- Advantages: instant, no trace left, easy to read.
- Limits: sensitive to the surface condition (dirt, rhodium plating) and less precise on certain alloys. So we cross-check it with another method.
Method 4: XRF analysis (the most precise)
Analysis by X-ray fluorescence (XRF) is the most advanced method. A device bombards the metal with X-rays and reads the exact composition of the alloy: the percentage of gold, but also of silver, copper, and so on.
- Advantages: completely non-destructive, very precise, gives the full composition.
- Limits: it mainly analyzes the surface (heavy plating can distort the reading if you don't test deeper), and the device is expensive.
The truth? No method is perfect on its own. A good professional cross-checks several tests to rule out any error — a plated piece that might pass a single check won't survive two. Do the mental test: if someone tells you a karat without checking anything, be wary.
Frequently Asked Questions
Does the acid test damage my jewelry?
Very little. It only requires a microscopic trace of metal on a touchstone, usually invisible on the piece. The electronic and XRF methods leave no mark at all.
Why not simply trust the hallmark?
Because it can be fake, worn, or misleading, especially on plated pieces. The hallmark points the way, but only a test confirms the real purity. It is a protection for you as much as for us.
Which method do you use at Jayma Or?
We combine methods depending on the piece, and we always carry out the check in front of you, explaining the result. Our goal is a fair, verifiable, and transparent estimate.
Can you test broken gold or scrap?
Yes, no problem. Broken gold, scrap, old jewelry, coins: everything can be tested. Purity and weight determine the value, regardless of condition.
Does gold-plated jewelry have a resale value?
Very little, because it contains only a thin layer of gold over a common metal. It is precisely to tell solid gold from plated that the purity check is essential.
Take action: have your gold's purity checked
You now know how gold purity is really verified — and why a single glance at the hallmark is not enough. The logical next step: have your jewelry tested by professionals.
Get a free, transparent estimate: send a photo of your jewelry by WhatsApp to +221 78 111 66 87, or make an appointment. We check the purity and weight in front of you, explain the calculation, and pay cash the same day.
Before you sell, demand the truth about your gold. Check the current rate, then write to us: you will know exactly what each piece contains.