You've inherited a gold necklace from your grandmother, bought a piece at a street market, or received gold jewellery as a gift from a source you're not certain about. You want to know: is this real gold, and what karatage is it? Several tests can give you useful information at home — though none replace professional XRF assay for definitive results on high-value pieces. Here are 8 methods, from simplest to most accurate.
Method 1: The BIS Hallmark Check (Fastest, Zero Cost)
What it tests: Government-certified purity declaration
How to do it: Look for the BIS HUID — a six-character alphanumeric code stamped or engraved on the piece (common locations: inside the ring band, on the clasp, on a separately attached hallmark plate). Download the BIS Care app (free on Android and iOS), go to "HUID Verification," enter the code, and confirm the karatage matches what you bought.
Accuracy: 100% if the hallmark is genuine and verifies on the BIS database. The limitation: hallmarks can be counterfeited on base-metal pieces. A genuine-looking stamp that doesn't verify on the BIS app is fraudulent.
When to use: Always first. If the HUID verifies correctly, you are done for most purposes.
Method 2: The Magnet Test (1 Minute, Nearly Free)
What it tests: Presence of ferrous (iron-based) metals
How to do it: Hold a strong neodymium magnet close to the piece. Real gold is not magnetic. If the piece moves toward the magnet, it contains iron, steel, or nickel.
Accuracy: Good at eliminating obvious fakes (iron-core pieces, steel-plated pieces). However: many non-gold metals (copper, brass, platinum, aluminium) are also non-magnetic. A piece that does not attract the magnet could be gold, brass, copper, platinum, or several other metals — not conclusive alone.
When to use: Quick first screen. If it fails (attracted to magnet) — not gold. If it passes — continue testing.
Method 3: The Float / Water Test (5 Minutes, Free)
What it tests: Approximate density
How to do it: Fill a glass or bowl with water. Place the gold piece in it. Real gold (density: 19.3 g/cm³) sinks immediately and decisively. Most base metals sink too, but at different rates.
Accuracy: Limited. Solid gold always sinks; hollow gold may float. Lead (used to add weight to fake pieces) also sinks. The test is most useful to identify hollow construction — if a "solid gold" ring floats, something is wrong.
Limitation: Does not distinguish gold from lead, platinum, or other dense metals.
Method 4: The Skin Discolouration Test (24 Hours Observation)
What it tests: Metal reaction with skin acids
How to do it: Wear the piece for several hours in normal conditions (some perspiration). Observe whether the skin underneath shows green discolouration (copper reaction) or black discolouration (silver oxidation). Pure 22K or 24K gold typically leaves no mark; lower-karat or plated pieces may cause greening or darkening.
Accuracy: Low as a standalone test. 22K gold can cause mild discolouration in high-sweat conditions (it contains ~8% copper). The absence of marks is consistent with higher-purity gold but not proof. Full explanation of skin reaction and jewellery here.
Method 5: The Ceramic / Unglazed Tile Test (5 Minutes, Low Cost)
What it tests: Metal streak colour
How to do it: Drag the gold piece across an unglazed ceramic tile (the back of a bathroom tile works). Observe the streak colour. Real gold leaves a yellow-gold streak. Base metals leave a black or grey streak.
Accuracy: Reasonable for distinguishing gold from iron or steel fakes. However: this leaves a scratch mark on the piece. Also, gold-plated copper may leave a yellow streak initially (from the plating) before the base metal shows. Not suitable for precious or heirloom pieces where scratching is unacceptable.
Method 6: The Vinegar Test (10 Minutes, Very Low Cost)
What it tests: Reaction to acetic acid
How to do it: Drop a small amount of white vinegar (or apply with a cotton swab) to the piece. Observe for 1–5 minutes. Base metals may show discolouration, oxidation, or slight colour change. Real gold is acid-resistant and shows no change.
Accuracy: Low. White vinegar's acidity is insufficient to definitively test higher-karat gold alloys. It may reveal obvious base metal pieces but will not distinguish 18K from 22K, or identify gold-plated pieces that have sufficient plating thickness to resist the weak acid. Use as a rough screen only.
Method 7: The Acid Test — Nitric Acid (Accurate, Requires Caution)
What it tests: Metal reaction to nitric acid — can estimate karatage
How to do it: This is the professional jeweller's field test. You need a testing stone (black basalt), testing needles (gold alloy at known karatages), and nitric acid in multiple strengths (18K, 22K acids are sold in test kits). Make a scratch mark from the piece on the testing stone; apply the appropriate-strength acid and observe the reaction.
- No reaction / slight gold colour retained = real gold at or above that acid's karatage
- Green reaction = base metal (copper) present at significant level
- Milky white = silver content
Accuracy: Good (80–90% reliable) when performed correctly. Better than most home tests at estimating karatage range.
Caution: Nitric acid is corrosive. Handle with gloves, eye protection, and adequate ventilation. Do not use near children. The test involves scratching the piece (minor surface damage).
Gold testing kits are available at jewellery supply stores and online (₹500–₹2,000 for a basic kit).
Method 8: XRF Professional Testing (Best Accuracy, Low Cost at Labs)
What it tests: Precise elemental composition — non-destructive
How to do it: Take the piece to a BIS-licensed assay lab or a jeweller with XRF equipment. The XRF gun fires X-rays at the piece and measures the fluorescent energy emitted by different metals to determine precise composition (e.g., "91.6% gold, 7.9% copper, 0.5% silver"). Result in 30 seconds. No scratching, no chemicals.
Accuracy: Very high (99%+). The current gold standard for non-destructive purity verification.
Cost: ₹200–₹500 at BIS-licensed assay labs. Find labs at bis.gov.in. Some large jewellers offer XRF testing for walk-in customers.
When to use: Any purchase above ₹25,000 without a verifiable HUID, inherited pieces of unknown origin, and any purchase where the seller's purity claim seems too good to be true.
The Density Test (Accurate for Simple Pieces, No Equipment Needed)
An honourable mention: measuring a piece's density mathematically. Weigh the piece in air, then weigh it suspended in water (use a thread and a scale that measures fractions of a gram). The difference is the water displacement — divide mass by displacement volume to get density. Gold's density is 19.3 g/cm³; brass is 8.5; platinum is 21.4. This is accurate for solid, non-hollow pieces and requires only a digital scale and a container of water.
Summary: Which Test for Which Situation
| Situation | Recommended Tests |
|---|---|
| Purchase from certified jeweller (new) | HUID verification (BIS Care app) |
| Online purchase on delivery | HUID verification + weigh on scale |
| Inherited piece, unknown origin | Magnet → Acid test → XRF at lab |
| Street market purchase (low value) | Magnet + float test + acid (if kit available) |
| High-value purchase from unknown seller | XRF at lab before completing payment |
| Second-hand purchase above ₹50,000 | HUID verification + XRF at lab |
Conclusion
No single home test definitively proves gold purity — especially for karatage determination. The HUID hallmark check (BIS Care app) is the fastest and most reliable for recent purchases. The acid test provides field-level karatage estimation for older pieces. XRF assay at a lab is the definitive answer for any high-value purchase where certainty matters. Full HUID hallmarking guide | Find verified jewellers near you.
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