How Does a Diamond Tester Work? Things You Should Know

A diamond tester is an important tool for those in the diamond industry and for those who purchase diamonds for personal use. This device is used to accurately determine whether a stone is a diamond, a diamond simulant, or a non-diamond gemstone. 

Typically, diamond testers can give an immediate and very reliable result, which is why it is used in many retail and professional settings. This guide will provide an overview of diamond testers and their uses, as well as some tips to help you choose the right tester for your needs.

What are Diamond Testers and How Do They Work?

A diamond tester is a device used to determine the authenticity of diamonds. It works by analyzing the electrical conductivity of the diamond, which is unique to each type of gemstone. Diamond testers can be used to distinguish a real diamond from other commonly used gemstones such as cubic zirconia, moissanite, and glass.

Diamond testers come in various types, from handheld devices to complex electronic units. The handheld version usually utilizes a needle-like probe that is inserted into the diamond. 

This probe is then pressed against the diamond's surface and a metal detector is used to detect the diamond's electrical conductivity. If the diamond is real, the metal detector will detect a response.

The more advanced electronic diamond tester is more accurate and can detect both fake and real diamonds. This type of tester uses infrared light to analyze the diamond's structure and density. If the diamond is real, the device will give a positive result. If the diamond is fake, the device will give a negative result.

Diamond testers are an essential tool for jewelers and diamond merchants. These testers can help them to determine the authenticity and quality of the diamond that they are selling, and also protect them from fraud

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Are Diamond Testers Accurate?

Diamond testers are highly accurate, often with a success rate of over 90%. The most common type of diamond testers are electronic diamond testers, which use thermal conductivity to measure the heat transfer of a stone. 

These testers compare the heat transfer rate of the stone to that of a known diamond and can accurately determine if the stone is a real diamond or not.

In addition to electronic testers, there are also manual diamond tests, which use a combination of physical and chemical tests to differentiate between real diamonds and fakes. For example, a manual tester may use a magnifying glass to look for flaws or inclusions that are often present in real diamonds, but not in fakes.

Related: Your Diamond Shape: What It Says About You

A manual tester may use a diamond testing solution to determine if a stone is a diamond. This solution will form a certain color when it comes into contact with a real diamond, but will form a different color when it comes into contact with a fake.

Overall, diamond testers are highly accurate and can be used to quickly and easily determine if a stone is a real diamond or a fake. This is especially useful for jewelers and gemologist, who need to make a quick determination on the worth of a diamond.

Types of Diamond Testers

The most common type of diamond tester is the electrical conductivity tester, which measures the diamond’s resistance to a current. This type of tester is effective in identifying whether or not a diamond is real. 

Other types of diamond testers include thermal testers, which measure the diamond's thermal conductivity and optical testers, which use a variety of techniques to identify the presence of a diamond. There are also diamond testers that use spectroscopy to measure the material’s optical properties. These testers are more expensive and complex

All types of diamond testers are useful for the detection of diamonds and for distinguishing between different types of diamonds. They are essential for anyone buying or selling diamonds, as they can help ensure that the diamond is genuine.

Related: Gem Cleaning: Do it Safe and Throughly

Common Fake Diamond Materials

If the diamond tester results in a negative result for a real diamond, there are many different materials the stone in question could be. Here are some of the most common used diamond alternatives.


a large cubic zirconia stone


Cubic Zirconia

Cubic zirconia has become a popular substitute for diamonds in recent times. It is an optically flawless, man-made crystal that is colorless, hard, and durable. It has been used as a diamond substitute for many years and has become more popular due to its affordability and near-diamond quality

While it does not possess the same value as a real diamond, cubic zirconia offers a similar look and feel at a much lower cost. It is also used to imitate colored diamonds such as pink or blue diamonds.

Related: Cubic Zirconia VS. Diamonds

White Zircon

White zircon is a gemstone that has been used as an imitation diamond for many years. It has a similar look and feel to a diamond, and is often used to create jewelry pieces that look like real diamonds. It has a high refractive index and dispersion, which gives it a sparkle that is similar to a diamond. White zircon is also very durable and can withstand a lot of wear and tear.


a pair of rings with a large moissanite gemstone



Moissanite is a diamond alternative that is increasingly popular for its affordability and look. It is a lab created gemstone made from silicon carbide. While it is not a true diamond, it is often used as a diamond substitute in jewelry. 

Moissanite is often more brilliant and sparkly than a diamond and has a unique refractive index which gives it a unique sparkle. It is also harder than a diamond and has a higher refractive index, meaning it can refract more light. Moissanite is often colorless, but can be found in yellow and even green. 

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Final Thoughts

Diamond testers are invaluable tools for gemologist, jewelers, and consumers alike. They provide a quick and reliable way to accurately identify diamonds and other gemstones, helping to ensure that buyers get exactly what they pay for. While diamond testers are not infallible, they are a reliable and cost-effective method of verifying that a diamond is genuine.