How to Check Purity of 20 Carat Gold

1. Introduction

• Brief explanation of what gold purity means: Gold is a precious metal of malleable physical nature. To make it usable, it is often mixed with other metals. Like all metals, the quality of gold too is determined by its purity. i.e. parts of gold in gold he metal.

• Quick mention of karats and how 20K fits between 18K and 22K: To determine the level of gold purity, it is measured in karats to standardise the percentage of metals which can be mixed in the alloy to achieve the desired strength and characteristics. Common purity levels available in the market are 24K which means gold in its purest form i.e. 99.99% purity, then we have 22K which means 91.6% purity and other available options being 18K and 14K

• Why verifying purity matters (value, trust, authenticity): Verifying the purity level of gold is essential from many aspects. It is instrumental in determining the value of the metal, as physically gold of different purity levels can be indistinguishable. Also, verifying purity can also help build trust during the transaction, and the authenticity of the metal.

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2. Understanding Gold Purity and Karat System

• Definition of karats: Gold purity is measured in karats (K) which signifies the amount or percentage of pure gold present in the alloy. Higher Karat of gold means a purer gold and vice versa.

• Mathematical breakdown:

• 24K = 24/24 parts gold i.e. 99.99%
• 22K = 22/24 parts gold i.e. 91.6%
• 20K = 20/24 parts gold ≈ 83.3%

• Comparison with other common purities (18K, 22K, 24K): 24K is gold in its purest form. It means that the metal is close to 99.99% pure, whereas lower karatage gold means other metals are mixed in the alloy to achieve hardness. 22K consists of 91.6% pure gold, the other 8.4% is a mix of other metals; this translates into a lower value compared to 24K pure gold. The same applies for other lower purity gold too.

3. Hallmarking: The First and Most Reliable Indicator

• What hallmarks are: Hallmarking is a process of stamping gold as per their purity level. It is a way of authorizing the purity levels by providing a readable stamp. Hallmarking is performed by the Bureau of Indian Standards (BIS). There are different hallmarks signifying different purity level. Most common one being the 916 hallmark used for 22K or 91.6% pure gold metal.

• Common stamps to look for: Hallmark stamps are provided on the metal to signify the purity. For jewelry is typically provided at the back side or non visible side of the jewellery, which is easy to find to validate the purity however not visible in daily wear.

• Possible variations depending on region: There could be possible variations in verifying authorities depending on the location where the gold was minted. Like BIS certifies gold purity in India, there could be other authorities providing certification in the other parts of the world.

4. Physical Appearance and Basic Checks

• Color comparison (20K vs lower/higher purity): Gold’s natural colour is yellow and lower purity gold i.e. a mix of other metals in the gold suppresses the natural yellow colour of the metal. This means that high purity gold will be yellower as compared to low purity gold metal.

• Magnet test (to detect non-gold metals): Gold does not attract to magnets naturally. The gold alloy with higher percentage of other ferrous metals are more likely to get attracted to magnets. Hence, magnets of various strengths are actively used to determine the purity of gold in the alloy. This is a famous and reliable test that can be done anywhere with the right tools.

• Limitations of physical tests: The biggest limitation of physical tests is that it is susceptible to user errors and bias.

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5. Acid Test: A Traditional Method

• How nitric acid test works: This is another reliable scientific test done to determine the purity of gold. In this test, the gold metal is rubbed on the stone and nitric acid is dropped on the residue left on the stone or the paper. Based on the colour changed by the acid, gold’s purity in the alloy is determined.

• Safety concerns and limitations: Gold testing using nitric acid can be unsafe for the tester since the testing individual needs to handle acid concentration to determine the test results and handling acid with untrained hands can result in accidents.

6. Electronic Gold Testing Devices

• Types of digital testers and how they operate: Due to modernization of equipment, there are now various types of electronic testers of various sizes and capabilities available in the market. These testers determine the weight and purity of the gold metal. This can be done by simply placing the gold in the machine.

• Pros and cons vs acid testing: Pro of using electronic devices as compared to acid testing is that it is safe, quick and reliable. Results in machine tests are also not prone to user error and bias. While there are not many cons, the only limitation of electronic gold testing compared to acid test is the higher cost to acquire the machine as well as costs related to operation and maintenance.

7. When to Seek Professional Certification

• Situations where expert evaluation is necessary: One may come across various situations where determining the gold purity can be a difficult task. Such situations arise due to lack of gold purity markers like hallmarks, unavailability of modern machine testers. Gold jewellery in a frail state which makes it unfeasible to test using nitric acid test, and even in case of old gold which may call for an expert opinion.

• Recognized certification body: In India, BIS (Bureau of Indian Standards) is the recognized body which can check and certify the purity of gold metal. The certification is done using a hallmark. There are various hallmarks for various purity levels.

8. Common Mistakes and Misconceptions

• Believing all stamped gold is pure: This is one of the biggest misconceptions. Stamping is done for various purity levels, the only purpose it serves is to certify the purity level. Also, only the BIS hallmark is a valid certification in India.

• Confusing 20K gold color with plating: 20K gold is 20/24 parts of pure gold in an alloy, whereas gold plating is when a thin layer of pure gold is applied on top of other metal to make it look like gold.

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