Whether you have just bought a piece of gold jewellery, inherited an old set from a grandmother, or pulled a coin out of a long-forgotten box, the question is the same: is it real, and how pure is it?

Home testing methods range from the genuinely useful to the popular-but-misleading. Some are physics-based and reliable. Some are urban myth. None of them are as definitive as a professional assay — but the right combination, applied carefully, can answer the question for the vast majority of household pieces.

This is a practical guide to verifying gold at home: which tests work, which don't, and when you should stop testing and take the piece to a professional.

Start with the hallmark

The most authoritative test for any modern piece sold in India is the BIS hallmark. Hallmarking has been mandatory for gold jewellery sold in India since June 2021, and every legitimately retailed piece carries four marks:

The HUID is the most useful of the four. Each piece has its own. Download the official BIS Care app on Android or iOS, enter the HUID, and the app returns the registered details for that specific piece — purity, weight, the licensed jeweller. If the HUID returns a match, the piece is verified.

Two important limitations. First, hallmarking is mandatory only on jewellery sold in India after June 2021; older pieces, inherited items, and gold bought abroad may not carry the BIS hallmark. Second, the HUID system is the most authoritative check available outside a professional assay — but it does not, on its own, rule out sophisticated counterfeits where a fake hallmark is etched onto a non-gold piece. For added safety, combine the hallmark check with at least one physical test below.

The magnet test

Gold is not magnetic. Holding a strong magnet near a gold item should produce no attraction. Neodymium magnets are most useful — they are inexpensive, small, and produce a much stronger field than refrigerator magnets.

If the piece is attracted to the magnet, it is not pure gold; it contains magnetic metals (iron, nickel, or steel). This is a useful first-pass test for gold-plated junk that has a base of magnetic metal.

The limit: many counterfeit techniques use non-magnetic base metals — copper, zinc, brass, or, most dangerously, tungsten. A gold-plated copper ring will pass the magnet test cleanly. A tungsten-core bar will pass the magnet test cleanly. The magnet test rules out the crudest fakes; it cannot, on its own, prove the piece is gold.

The density (water displacement) test

Gold's defining physical property is its density: 19.3 grams per cubic centimetre. This is more than twice the density of brass and several times the density of most other commonly-substituted metals. For solid pieces of meaningful size, density is the most reliable home test.

How to do it.

  1. Weigh the piece on a precise scale, in grams. Note the weight.
  2. Fill a graduated cylinder or measuring cup with water; note the starting volume in millilitres.
  3. Tie a thin thread to the piece (or use tweezers) and lower it fully into the water without touching the sides. Note the new volume.
  4. Subtract starting volume from new volume to get displaced volume in millilitres (which equals cubic centimetres).
  5. Divide weight by volume. The result is the density in grams per cubic centimetre.

For pure 24K (999) gold, expect a density very close to 19.3 g/cm³. For 22K (916), expect roughly 17.7-17.9 g/cm³ depending on the alloy. For 18K (750), expect 14.8-15.5 g/cm³. Lower readings indicate the piece is either not gold or contains substantially less gold than claimed.

The density test is the strongest single home check for solid pieces. It does have one major blind spot: tungsten, with a density of 19.25 g/cm³, is nearly indistinguishable from gold by water displacement. A tungsten-cored bar wrapped in a thin layer of real gold will pass a density test. This is rare for jewellery (tungsten is brittle and cannot be worked into ornate forms) but a genuine concern for bullion.

The ceramic scratch test

Gold is soft and chemically inert. Dragging a real gold piece across an unglazed ceramic surface — the unglazed underside of a porcelain plate works — will leave a faint golden streak. A gold-plated piece, once the plating is breached, will leave a dark grey or black streak from the underlying base metal.

This test is destructive in a small way: it scratches the piece. Use it on the back of a piece, a hidden edge, or only on items where a small mark is acceptable. It is most useful on rings, chains, or small ornaments where a discreet test mark is hidden when the piece is worn.

Visual and weight checks

Some indications come from how the piece looks and feels.

Colour. Pure gold is a deep yellow with a slight orange undertone. Gold-plated items can look brassy or have an unnaturally bright yellow. Worn plating often shows a slight green or pink tinge as the base metal becomes visible at edges.

Wear patterns. Examine the high-friction areas: the inner band of a ring, the back of a clasp, the underside of a pendant. Gold-plated pieces wear through to base metal at these points; real gold wears uniformly.

Stamping quality. Genuine BIS hallmarks are crisp and consistent. Counterfeit hallmarks are often slightly blurry, off-centre, or have inconsistent character spacing. A magnifying glass (10x loupe) is useful here.

Weight relative to volume. Pick up the piece and feel it. Gold is dense; a real gold ring feels surprisingly heavy for its size. A piece that feels light for its appearance is suspicious.

Acid tests — useful, but not for amateurs

Professional jewellers and assayers use nitric acid (and aqua regia for higher karats) to test gold. The principle: acid reacts with base metals but not with gold. A genuine gold piece should resist nitric acid; a plated or alloyed piece will show discolouration or fizzing where the acid touches it.

Home acid testing kits exist and work, with three serious caveats.

Safety. Nitric acid is highly corrosive and produces toxic fumes. It must be used outdoors or with proper ventilation, with gloves and eye protection, and never near children, pets, or unprotected surfaces.

Damage to the piece. Acid testing scratches and stains. It is appropriate for unmarked, low-value pieces being assessed for resale. It is not appropriate for valued jewellery or anything sentimental.

It can miss sophisticated counterfeits. A counterfeit piece with a thick gold-plated outer layer will pass an acid test until the acid penetrates through to the base metal. Modern counterfeits with thicker gold cladding can defeat surface-level acid testing.

For most household purposes, acid testing is overkill. The hallmark, magnet, and density tests, used together, do the same work without the chemical hazard.

Tests to ignore

Several "home tests" circulate widely but are unreliable.

The vinegar test. Dropping vinegar on gold "should" produce no reaction. In practice, vinegar is too weak to react with most base metals quickly, so a gold-plated copper piece can pass a vinegar test. Useful as a very crude screen at best.

The skin test. The claim that real gold leaves no mark on the skin while fake gold leaves a green or black mark is partly true (acidic perspiration reacts with copper alloys) but unreliable as a diagnostic. Skin chemistry varies, and even some real low-karat gold alloys can produce skin reactions.

The float test. Real gold is dense and sinks. So does almost everything else metal-based. The float test only rules out very lightweight non-metals; it has no meaningful diagnostic value for jewellery.

The bite test. Famously associated with Olympic medals. Real gold is soft and should dent slightly when bitten. Lead is also soft, gold-plated lead passes the bite test cleanly, and biting any metal piece is a dental risk and a hygiene problem. Don't.

What home tests cannot catch

Two types of counterfeits defeat almost every home test.

Tungsten-cored bars. Tungsten has a density of 19.25 g/cm³, fractionally below gold's 19.3. A tungsten bar wrapped in real gold passes the magnet test (tungsten is not magnetic), passes the density test (within a margin too small to detect with a kitchen scale), and passes a surface acid test (the outer gold layer reacts as expected). The only home check that detects tungsten cores reliably is the ring (sound) test — gold has a distinctive musical ring when struck; tungsten produces a duller sound — but this is subjective and easy to misjudge.

High-quality plating with thick gold cladding. Modern gold-filled and gold-clad pieces have an outer gold layer thick enough to pass casual acid testing and even some XRF surface scans. The piece looks gold, weighs roughly right for its volume (because the base metal is itself dense), and resists basic chemical tests.

For high-value pieces, especially bars or coins above a few grams, home testing is not enough.

When to escalate to professional testing

Escalate to a qualified assayer or jeweller if any of the following apply.

Professional methods include XRF (X-ray fluorescence) spectrometry, which identifies the elements at the surface of a piece without damage; ultrasonic testing, which can detect inhomogeneities like a tungsten core; and electromagnetic conductivity testing, which detects whether the interior conductivity matches gold's profile. BIS-licensed assaying centres in major Indian cities offer all of these as paid services, typically at modest cost relative to the value of the piece being tested.

The layered approach

No single home test is definitive. The right approach is layered:

  1. Check the BIS hallmark and verify the HUID via the BIS Care app
  2. Run the magnet test as a quick screen
  3. Run the density test on solid pieces
  4. Check colour, wear, weight, and stamping quality visually
  5. Escalate to a professional assay if anything looks off, or for any high-value piece

Each layer rules out a different category of fake. A piece that passes all of them is, with very high confidence, real gold of the stated purity. A piece that fails any one of them deserves a closer look before you trust it.

Gold rewards precision. The five minutes spent verifying a piece at home — or the small fee for a professional assay on something significant — is the cheapest insurance you will buy on what is otherwise a meaningful asset.