Why Checking Gold Purity Matters

When buying gold jewellery, coins, biscuits, or bars, the most crucial factor is gold purity. Not only does purity affect the price, but it also determines durability, resale value, and authenticity.

Whether you're purchasing a necklace or investing in a gold bar, verifying purity ensures you're getting what you paid for.

In an era of smart buying, it’s vital to know how to test gold at home, online, or at the shop.

Know Gold Karat and Purity Levels

Gold purity is measured in karats (k), where 24k gold purity represents 99.9% pure gold. Lower karats have gold mixed with other metals for strength.

24K Gold Purity

24k gold is the purest form available, commonly used for coins and investment-grade gold bars. It’s bright yellow and soft, hence not ideal for jewellery that faces daily wear.

Significance of 22K Gold Purity in Jewellery

22k gold purity (91.6% pure gold) is ideal for jewellery. It strikes a balance between strength and richness. If you see "916 gold purity", that’s 22k gold, perfect for ornaments.

Overview of 18 Karat Gold Purity

18 karat gold purity contains 75% gold and 25% other metals, offering better durability and is common in stylish, designer, minimal jewellery. It’s great for those who want a modern look with affordability.

Methods to Test Gold Purity at Home

Can you check the gold purity at home? Absolutely. These simple methods don’t require expensive tools.

1. Magnet Test

Materials Needed:

• Strong magnet (e.g., neodymium magnet)

Steps:

1. Hold the magnet near the gold item.
2. Gold is not magnetic. If the item is attracted to the magnet, it's fake or alloyed with magnetic metals.

Pros: Quick, easy
Cons: Can only detect fakes with magnetic metals; not a purity test

2. Float Test (Density Check)

Materials Needed:

• A cup of water

Steps:

1. Drop the item in water.
2. Authentic gold, being remarkably dense, offers no buoyancy and sinks without delay.
3. If it floats or sinks slowly, it's likely fake or a low-purity alloy.

Pros: Simple
Cons: Not accurate for karat testing; more of a fake detector

3. Weight and Volume Method (Density Test)

Materials Needed:

• Precision scale
• Graduated cylinder (or water displacement container)

Steps:

1. Weigh the gold item (in grams).
2. Fill the cylinder with water, and record volume.
3. Submerge the gold, record a new volume.
4. Subtract to find the volume of the item (in mL = cm³).
5. Calculate density: Density = Weight / Volume

• Pure gold density ≈ 19.3 g/cm³

Pros: Scientific approach, no damage
Cons: Needs precise tools; best for small, solid pieces

4. Visual Inspection and Hallmark Check

Steps:

1. Look for stamps like “10K”, “14K”, “18K”, “22K”, or “999”.
2. Use a magnifying glass to inspect authenticity.

Pros: Non-invasive, instant
Cons: Stamps can be faked or worn off

5. Ceramic Plate Test

Materials Needed:

• Unglazed white ceramic tile

Steps:

1. Drag the gold item across the tile.
2. Real gold leaves a golden streak; fake leaves black or green marks.

Pros: Quick, easy
Cons: Can scratch the item

6. Using Vinegar or Lemon Juice (Without Acid)

Put a drop of vinegar or lemon juice on the gold. If the metal changes colour, it's not real gold. This is a quick way to test without acid.

Not sure which gold purity to choose? Discover the differences in our guide on which karat gold is best for jewellery.

7. Acid Test (Nitric Acid Test)

Materials Needed:

• Gold testing kit (acid bottles for different karats: 10K, 14K, 18K, 22K, etc.)
• Scratch stone (usually included in kits)
• Gloves and safety goggles (for protection)

Steps:

1. Rub the gold item on the scratch stone to leave a visible mark.
2. Apply a drop of acid corresponding to a known karat value.
3. Observe the reaction:

• No reaction = gold is of equal or higher purity than the test acid.
• Fades or dissolves = gold is of lower purity.

Pros: Reliable, relatively inexpensive
Cons: Involves chemicals; can damage jewellery if applied directly

8. Electronic Gold Tester

Materials Needed:

• Digital gold tester (e.g., Kee Gold Tester)

Steps:

1. Calibrate the tester.
2. Place the probe on the gold surface.
3. The machine gives a digital reading of the karat value.

Pros: Accurate, fast, non-destructive
Cons: Expensive, needs calibration

Check at a Shop or Jeweller

Most jewellers offer testing services.

Here’s how they do it:

Karat Meter Test (Without Machine Option)

A karat meter uses XRF technology to detect purity accurately. However, experienced jewellers can also identify karats manually through their skills and hallmark stamps, without machines.

Online Tools to Check Gold Purity

1. BIS CARE App

The BIS CARE app allows you to verify the authenticity of your gold jewellery by scanning its Hallmark Unique Identification (HUID) number.

Steps:

1. Access the BIS CARE app – simply search for it on the Google Play Store for Android or the Apple App Store for iOS.
2. Inside the app, tap 'Verify HUID'.
3. To proceed, enter the unique 6-character HUID found on your gold.
4. The app will display details such as:

• Purity of gold
• Jeweller’s registration number
• Assaying & Hallmarking Centre name and address
• Date of hallmarking
• Type of article (e.g., ring, chain)

2. BIS Hallmarking Portal

Alternatively, you can verify the HUID online through the BIS Hallmarking Portal:

1. Visit the BIS Hallmarking Portal
2. To find your item, type your HUID code into the field and select "Search".
3. The portal will provide similar details as the app, confirming the authenticity of your gold jewellery.

How to Identify Hallmarks on Gold Jewellery

Look for these 4 hallmarking symbols:

1. BIS logo
2. Purity in karat and fineness (e.g., 22K916)
3. HUID number
4. Jeweller’s registration number

These marks are engraved on gold jewellery to confirm authenticity.

Learn how to identify original hallmark gold jewellery in our detailed guide.

Gold Coin and Biscuit Purity

Investors and collectors often buy gold coins and gold biscuits. But how do you test their purity?

Hallmarking and Weight Confirmation

Genuine coins carry the same hallmark as jewellery. Always buy from BIS-certified sellers and ask for weight confirmation.

Gold Bar and Large Investment Gold Purity

Large purchases like gold bars require even stricter verification.

Purity Reports and Hallmark for Gold Bars

Ensure the bar has a hallmark, a purity certificate, and an original invoice. It should clearly mention 24k gold purity or equivalent fineness like 999.

Want your gold to look like new? Here’s how to safely clean gold jewellery at home.

Final Thoughts

Discovering the purity of gold is simple: start at home, use a hallmark check, HUID verification via the BIS Care app, then confirm online or at the shop with experts. Whether you’re buying a gold bar, biscuit, coin, or jewellery.

FAQs

1. How can you check gold purity at home without acid?
Use the float test, magnet test, or vinegar test for safe at-home purity checks.

2. What does 916 mean in gold?
916 means the gold is 91.6% pure, equivalent to 22 karats.

3. Can you check my jewellery’s authenticity online?
Yes! Use the BIS Care App or visit the BIS website to enter the HUID number.

4. Is hallmarking mandatory in India?
Yes, BIS hallmarking is mandatory for gold jewellery sold in India.

5. What’s the best way to verify a gold coin’s purity?
Ensure it’s hallmarked, has a serial number, and buy from certified brands.

6. Can you trust gold tested without a machine?
Yes, experienced jewellers can provide accurate tests using certified tools or techniques.

7. How can you test gold purity at home?
Use a gold testing kit, magnet test, float test, or acid test. You can also check the hallmark stamp.

8. How to know if gold is 22K or 24K?
Check the hallmark:

• 22K = “916”
• 24K = “999”
  Use a gold testing machine or acid kit for accuracy.

9. How to verify if gold is real?
Do a magnet test (real gold is not magnetic), acid test, float test (real gold sinks), or get it tested professionally.

10. How to check gold instantly?
Use a magnet or inspect for a hallmark. A gold testing pen or machine gives quick results.

11. Can lemon test gold?
Yes, real gold won’t react to lemon juice. Fake gold may change colour due to the acid content.

12. What is KDM gold?
KDM gold is 92% gold (22K) alloyed with cadmium (8%). It was used for soldering, but is now avoided due to toxicity.

13. How to check gold purity with water?
Drop it in water, real gold sinks. Not very accurate for purity, but it can help check authenticity.

14. Is 22K more expensive than 24K?
No, 24K is more expensive because it’s purer (99.9% gold vs. 91.6% in 22K).

15. How to test gold with toothpaste?
Rub gold with white toothpaste and rinse. Real gold won’t change; fake may tarnish. Not very reliable.

16. How to detect gold using the phone?
Some apps claim to use metal detection via a phone's magnetic sensor, but phones can't accurately detect real gold as it's non-magnetic.