Common Home Tests and Their Reliability
Several home tests are commonly used to check gold, but most are unreliable for precise purity assessment. The magnet test is useful for ruling out obvious fakes — real gold is non-magnetic, so if a piece is strongly attracted to a magnet, it likely contains ferrous metal. However, the test cannot distinguish between 22K and 18K gold or confirm purity.
The nitric acid test (applicable only if you have the right acid) shows that gold resists corrosion — a piece that bubbles or dissolves is likely low-quality or plated. But applying acid without proper facilities is hazardous and still only gives a rough indication. The skin discolouration test — where fake gold often leaves green or black marks on skin from copper or zinc oxidising — is too imprecise to rely on for a selling decision.
Reading the Hallmark: The Most Accessible Check
The most practical pre-sale check available to any seller is to look for the BIS hallmark and fineness stamp. Using a magnifying glass, look on the inner surface of bangles and rings, the clasp or fastening of necklaces, and the post of earrings. You should see the fineness number (916, 750, etc.) and, on pieces made after 2021, a six-digit HUID code.
If the HUID code is present, verify it on the BIS Care app — this confirms the piece was genuinely tested at a BIS-recognised centre and that the purity is as marked. This is the most reliable non-laboratory check available to a retail seller in India.
Do not rely on appearance: High-quality gold-plated jewellery can pass a visual inspection and even fool the magnet test. Gold-filled items (a thick gold layer over a base metal) also resist many home tests. Only XRF or fire assay can definitively confirm purity — any home method is at best a preliminary screen.
Protecting Yourself from Unfair Offers at the Selling Counter
When you arrive at a gold buyer with your pre-checked jewellery, the buyer will conduct their own test. Your role is to verify that test is fair. Request XRF testing, watch the screen, and note the purity result. Compare it to the hallmark or to any independent test result you obtained in advance.
If the buyer's XRF result is significantly different from the hallmark — more than 10 fineness points lower — ask for an explanation or seek a second opinion from another buyer. Discrepancies between a certified BIS hallmark and an XRF result can sometimes reflect calibration issues with the buyer's machine. A genuinely well-calibrated XRF should closely match the BIS-certified purity.
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