How to Check Gold Purity at Home: A Practical Guide for Indian Buyers

Method 1: Check the BIS Hallmark (Most Reliable)

The Bureau of Indian Standards (BIS) hallmark is your strongest guarantee of gold purity in India. Since September 2021, selling gold jewellery without BIS hallmarking is illegal for registered jewellers. A hallmarked piece will carry three distinct marks stamped on the jewellery itself:

• The BIS logo — a triangle with inward arrows, indicating certified testing
• The karat and fineness mark — e.g., “22K916” for 22 karat gold, “24K999” for 24 karat
• The HUID — a 6-character alphanumeric Hallmark Unique Identification number

Use a magnifying glass to examine the piece carefully. Genuine hallmarks are laser-engraved and crisp. Counterfeit marks are often blurry, inconsistently placed, or missing one of the three required elements.

Method 2: Verify the HUID on the BIS Care App

The most authoritative way to confirm a hallmarked piece is to check the HUID number on the official BIS Care mobile application, available on both Android and iOS. Enter the 6-character HUID, and the app will display the registered details of the jewellery piece — the jeweller who submitted it for hallmarking, the assaying centre that tested it, the karat purity, and the metal weight. If the HUID does not appear in the database, treat it as a serious red flag.

You can also verify HUIDs on the BIS website at bis.gov.in. This verification takes under a minute and is the most definitive check available to consumers. Make it a habit to verify before every purchase.

Method 3: The Magnet Test

Pure gold is not magnetic. If you hold a strong magnet (a neodymium magnet works best — available cheaply online) near a gold piece and it is attracted to the magnet, the piece definitely contains a significant amount of iron, nickel, or other ferrous metals that have no place in genuine gold jewellery.

However, passing the magnet test alone does not confirm purity. Many non-gold metals — silver, copper, aluminium — are also non-magnetic and can be used to adulterate gold without triggering a magnetic response. The magnet test is useful as a quick filter to rule out obviously fake pieces, but should not be relied upon as the sole verification.

Method 4: The Float Test

Gold is exceptionally dense — at 19.3 grams per cubic centimetre, it is significantly heavier than most metals used to counterfeit it. Drop your gold piece into a glass of water. Genuine gold of significant purity will sink immediately and rest at the bottom. If the piece floats, or sinks slowly, it is likely hollow, plated over a lighter metal, or not genuine gold at all.

This test is not foolproof for thin, lightweight jewellery. Very fine chains and thin bangles may behave unexpectedly due to surface tension. It works best with solid pieces such as coins, bars, and thick bangles.

Method 5: The Skin Test

Pure gold does not react with sweat or skin. If wearing a gold piece consistently leaves green or black marks on your skin, it almost certainly contains copper, nickel, or other base metals in significant proportions. High-purity 22K or 24K gold will not cause any discolouration. This is more useful as an ex-post indicator — a piece that has already turned skin green is very likely adulterated.

Method 6: The Acid Test (for Advanced Verification)

Gold testing acid kits are available from jewellery supply stores for around ₹500–₹1,000. The acid test involves rubbing the gold piece against a black testing stone to leave a streak of metal, then applying a drop of nitric acid of known concentration. Different karats of gold react differently to the acid:

• 14K gold acid: If the streak dissolves, purity is below 14K; if it remains, purity is 14K or above
• 18K gold acid: More concentrated — only 18K+ survives
• 22K gold acid: Used for standard Indian jewellery verification

Handle acid test kits with care — nitric acid is corrosive and requires safety precautions. For consumers, this test is generally best left to professional goldsmiths or assaying centres. It is mentioned here for completeness, but the BIS HUID verification is far simpler and equally definitive.

What to Do If You Suspect Fake Gold

If you have purchased jewellery that fails the above tests, you have the following options:

• Take the piece to an independent BIS-registered Assaying and Hallmarking Centre (AHC) for a formal purity test — this costs ₹35–₹200 and provides a certified result
• File a complaint on the BIS Consumer Complaint Portal or call the BIS helpline (1800-11-4000 toll free) if the hallmark appears fraudulent
• Contact your local consumer forum under the Consumer Protection Act 2019 if you have been defrauded by a jeweller

Best Practice: Always Insist on the Bill

Regardless of the purity test you conduct, always insist on a detailed purchase bill from the jeweller. The bill should state the weight of the gold (net and gross), the karat purity, the making charges separately, and the GST component. A jeweller who refuses to provide a proper bill is a significant red flag. Under GST rules, gold purchases from registered jewellers must be accompanied by a proper invoice — non-compliance is itself a reportable offence.