Best Diamond Tester

Diamond is a precious stone commonly used to make expensive rings, necklaces, and other classy jewelry. However, imitations, simulants, or moissanite are available in the market. These artificial stones look like diamonds and share many properties with natural stones. Unfortunately, these are sold to unsuspecting customers or dealers as genuine diamonds. That is why you need a diamond tester.

A diamond tester is an electronic device that determines the genuineness of diamonds. If you care about the originality of the products you sell to your customers, it pays as a dealer to have one. And as a customer, you need to spend your hard-earned money on genuine diamond products. Having a diamond tester is the only way to avoid being duped by unscrupulous traders.

Diamond testers are of two different types, depending on the working principle. These include heat diamond testers and electric diamond testers. Thermal diamond detectors use the different thermal conductivity of materials to determine the quality of the diamond. They emit heat from the tip and read the speed at which heat passes through the material under test, in this case, diamond.

On the other hand, electric diamond testers use varying electrical conductivity of materials to determine the quality of the diamond. They are the most accurate and reliable but have a high price tag. They are most commonly used by jewelers.

Diamond tester

Read on as we review the best diamond testers you can buy for testing diamonds. We have extensively researched and picked the best products across different price ranges. So, you can find what suits your budget.

Top 13 Best Diamond Tester Reviews in 2024

The best way to know genuine diamond products is by using a reliable diamond tester. It is nearly impossible to distinguish replicas or simulants from the original diamond stone with the naked eye. That’s why we have reviewed and recommended the following products for you:

1. Presidium Adamas Diamond and Moissanite Tester (Best Overall)

Presidium Adamas Diamond and Moissanite Tester Authenticating Diamonds

The first and the most accurate and reliable tester for authenticating diamonds is the Presidium Adamas Diamond and Moissanite Tester. It is the best for jewelers because it does more than detect diamonds. You can use it for detecting moissanite, simulants, and other replicas with metal alert.

This diamond tester boasts the industry’s thinnest probe for accurate testing of small colorless diamonds, as small as 0.02 carats, and diamond melees as small as 0.01 carats. It also features a bright LED display that provides visible results. Besides, the Presidium Adamas Diamond and Moissanite Tester shut off automatically after 2 minutes of inactivity to conserve battery power.

Presidium Adamas Diamond and Moissanite Tester also feature easy-to-use, interchangeable probes without downtime. It also has built-in memory that stores up to 500 previous readings for reference.


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  • Accurate
  • Lightweight and portable
  • Dual power source
  • Built-in memory chip
  • Precise and reliable
  • Built-in memory to store up to 500 previous test records


  • Very expensive

2. Presidium Instruments Gem Tester II (PGT II)

Presidium Instruments Gem Tester II (PGT II) with Assisted Thermal Calibration (ATC) for Identifying Diamonds Moissanites and Common Colored Gemstones

Presidium Instruments Gem Tester II  (PGT II)  is the second-best diamond tester on this list. The unique feature of this device is the assisted thermal calibration that allows you to self-calibrate it to suit your testing environment.

The PGT II can accurately identify diamonds, moissanite, and the most common colored gemstones. Like the first choice, it also has a thin probe with a retractable tip to accurately determine the quality of diamonds. It is, however, more compact, sturdy, and portable.

This device is also versatile and reliable. It can differentiate up to 16 gemstone types, with the results clearly indicated on its analog dial interface. Regarding ease of use, PGT II comes first.


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  • Stones can be polished/unpolished
  • Consistent and accurate
  • Versatile – identifies up to 16 different gemstones
  • Thin probe for use on smaller stones
  • Easy to use


  • Relatively expensive

3. HDE Diamond Tester Pen

HDE Jeweler Diamond Tester

Choose HDE Diamond Tester Pen if you want the best budget diamond tester. At an affordable price range, you get a good product for authenticating diamonds.

HDE Diamond Tester Pen is an indispensable diamond tester for jewelry lovers. It is also great if you want to start a business in this industry and don’t want to deal with cases of circulating fake diamond jewelry.

This device is accurate, user-friendly, affordable, and portable. It easily fits into your pocket and can be carried anywhere without notice. Whether you need to test diamond bracelets, rings, necklaces, earrings, or loose diamonds, this product comes in handy.


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  • Very affordable
  • Compact and portable
  • Accurate and reliable
  • Easy to use for both novices and experts


  • Does not test other gemstones

4. SmartPro SPGE-I Diamond Tester

SmartPro SPGE-I Gem Eye I Gem and Diamond Tester Smart Pro

SmartPro SPGE-I is a reliable gemstone tester with a color estimator display. It instantly tests diamonds and all their simulants using the thermal conductivity principle. Diamonds have a unique thermal conductivity that is not easy to replicate.

The device has two thermocouples; one is heated electronically while the other is cooled by the gemstone under test. The difference between the temperatures is amplified and displayed on the analog dial on the SmartPro SPGE-I’s interface.

SmartPro SPGE-I is an easy-to-use diamond tester with a color estimator display to help you test gemstones and diamonds.


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  • Highly efficient
  • Identifies metals, simulants, and diamonds instantly
  • Easy-to-use
  • Portable and can be used anywhere


  • Very expensive

5. Presidium Instruments Gem Indicator (PGI) Handheld Tester

Presidium Instruments Gem Indicator (PGI) Handheld Tester for Identifying Diamonds and Common Colored Gemstones

Another diamond tester from Presidium instruments is the GEM Indicator handheld tester . It inherits all the properties and features of the product from this brand but a unique pen design to enhance portability and usability.

The PGI handheld test can accurately identify diamonds and other most common, colored gemstones, giving results in under six seconds. It has a thin retractable thermoelectric probe tip. This ensures constant pressure between the stone under the test and the probe for better accuracy.

This device uses a clear digital LED screen to display the results. It can intelligently identify up to 31 gemstones, making it one of the most versatile diamond testers. PGI handheld diamond tester also has color input functions that separate different stones for more precise, easy-to-read results.

PGI diamond tester is ergonomically designed for ease of use. It has a sleek chrome-brushed finish to offer grip when held by hands.


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  • Highly versatile – identifies up to 31 different gemstones
  • Clear digital LED display screen for showing test results accurately.
  • Handheld design enhances portability and usability
  • Ideal for both novice and professional jewelers
  • Accurate and reliable


  • Relatively expensive

6. Gemoro Testerossa Diamond Tester

GemOro Testerossa Diamond Tester

Gemoro Testerossa is an ideal tool if you are looking for an electric diamond tester for separating diamonds from their simulants. It uses a new enhanced moissanite testing technology that accurately detects low-conductivity stones, such as white sapphire and moissanite.

Gemoro Testerossa diamond tester features an LED stone illumination and UV fluorescence detection. Its retractable probe tip is hardened to withstand regular use, which is why this diamond tester has an unprecedented 10-year probe tip warranty. It is designed to last forever. Once you buy it, you will not budget for any diamond tester in decades.

This diamond tester comes from a company with over 50 years of experience making diamond, moissanite, and white sapphire testing devices. Its products are of the best quality and the most reliable.


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  • Quick warm-up time
  • Sturdy and covered tip
  • Comfortable grip
  • High quality
  • Highly durable, with probe tip having a 10-year warranty


  • Cone indicator can malfunction
  • Relatively expensive

7. Presidium SDS Synthetic Diamond Screener

Presidium SDS Synthetic Diamond Screener

Presidium SDS Synthetic Diamond Screener is a type of diamond tester with additional features to distinguish between colorless type IA and IIA diamonds. It achieves this through the UV absorption of synthetic diamonds.

Synthetic diamonds are created through chemical vapor deposition (CVD) or high-pressure high-temperature (HPHT) syntheses. These have different UV absorption properties from natural colorless diamonds. When this tester subjects them to UV irradiation, each diamond type absorbs different amounts of UV light, which makes it possible to distinguish them.

Presidium SDS Synthetic Diamond Screener uses blue and red colors to indicate the results. The blue one shows a natural diamond, while the red one shows a type IIA diamond.


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  • Instantaneous clear results
  • Easy to use and interpret results
  • Tests diamond melees as small as 0.02 carats


  • Can only distinguish between colorless type IA and IIA diamonds

8. Presidium Multi Tester III (PMuT III)

Presidium Multi Tester III (PMuT III) All-in-One Instrument for Testing Diamonds, Moissanites and Diamond Simulants

Presidium Multi Tester III is an all-in-one instrument for testing diamonds, moissanite, and diamond simulants. It is characterized by a handheld design and easy-to-use interface with a rubberized anti-slip grip for comfort and handling. But it requires calibration before use.

Like all other diamond testers from this manufacturer, the PMuT III features a thin retractable probe tip that guarantees maximum pressure between the gemstone and the probe tip. This ensures accurate results. And given its probe tip size of 0.6mm, this device can test colorless, small diamonds up to 0.02 carats.

The PMuT III diamond tester has a 180-degree multi-viewing LED display to enhance the readability of test results. It is ideal for either left or right-hand use.


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  • Consistent and reliable results
  • Simple and easy to use
  • Light and portable
  • Clear and visible display


  • Relatively expensive

9. Presidium Diamondmate-C Electronic Diamond Tester

Presidium Diamondmate-C Electronic Diamond Tester

Presidium Diamondmate-C is an electronic diamond tester that can instantly authenticate diamonds. Like all products from Presidium, this device features a thin probe tip that tests diamond pieces as small as 0.02 ct. Its retractable thermoelectric probe enhances accuracy by ensuring constant pressure between the gemstone under test and the probe tip.

This diamond tester features a metal alert buzzer and other features for consistent results. Another unique feature is its rechargeable battery that provides up to 6 hours of continuous operation on a single charge.


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  • Easy-to-read LED light display
  • Test both polished and unpolished gemstones
  • Easy to use, consistent and reliable results every time
  • Compact, lightweight, and portable
  • Provides up to 6 hours of continuous use
  • Rechargeable battery operated


  • Relatively expensive

10. TEKCOPLUS DMTK-83 Diamond Tester

TEKCOPLUS DMTK-83 Diamond Tester

TEKCOPLUS DMTK-83 Diamond Tester is designed to help differentiate diamond and moissanite from other fake stones quickly and accurately. It features a thin elastic-tipped probe to enhance accuracy when testing and identifying small gemstones up to 2pt.

This device features an adjustable LED bar graph for matching different stone sizes and a beep indicator, which alerts you about the results.


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  • Simple and precise operation
  • Make audible sounds to provide an accurate reading
  • Relatively affordable
  • Portable and easy to use
  • Provides accurate readings
  • Has a short warm-up time of just 25 seconds
  • Provides up to two hours of continuous use on a single charge


  • Mostly accurate only when testing large stones

11. StillCool Diamond Tester

StillCool Diamond Tester

Once again, if you have a tight budget, consider the the StillCool diamond tester. This device costs low but offers the best features, including LCD and LED indicators. It is mainly designed for quick and accurate diamond testing, making it easy to distinguish between the original stone and its simulants.

StillCool is a highly portable electronic device for both novice and professional jewelers. With this tool, you won’t worry about replicas or simulants doing rounds in the industry. It does not react with fake stones, such as cubic zirconia.


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  • Portable
  • Very affordable
  • Visual and audible indicators for accurate results
  • Ideal for novices


  • Not as accurate
  • Only works on diamonds

12. Hqdz Diamond Selector II

Hqdz Diamond Selector II

Another affordable diamond tester option is the Hqdz Diamond Selector II. This device is an accurate diamond testing tool for any jeweler who wants to authenticate a diamond. Like many other products on this list, it is designed for quick and precise diamond testing.

The intuitive user interface of this diamond tester makes it ideal for different uses. It has an LCD and LED indicators for showing results when testing gemstones. Additionally, the tester emits an audible sound to help differentiate the readings.

The Hqdz Diamond Selector II is easy to operate. You don’t need any skills to use this device to test different diamonds. All you should do is turn it on and slightly press the gemstone on its probe tip. It will not beep for any fake stone. This diamond tester has numbered LED lights that tell you whether the stone is glass, original jade, crystal, or diamond. The user manual has information regarding result interpretation.


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  • Portable
  • Very affordable
  • Visual and audible indicators for accurate results
  • Ideal for novices


  • Not as accurate
  • Only works on diamonds

13. Molo DT-1 Diamond Tester

Molo DT-1 Diamond Tester

Molo’s diamond tester is the last product on the list of the best diamond testers. Its features are the same as the previous two products, but with slight differences. This includes LEDs that light up and an audible sound when the test is complete. You can then read the indicated test results to determine the authenticity of the diamond.

The diamond tester remains mute for fake stones. But if the gemstone tested is genuine, it lights up a row of LED lights to correspond with the test results.

This Molo DT-1 diamond tester is lightweight and portable. It can fit in any pocket or purse to easily carry it when going to a garage sale, flea market, or any other jewelry appraisal event.


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  • Portable
  • Very affordable
  • Visual and audible indicators for accurate results
  • Ideal for novices – easy to use


  • Can only test for diamonds

Best Diamond Tester Buying Guide

Choosing the best diamond tester in the market flooded with different products requires information about these devices. There are factors to consider, and that is what this buying guide will focus on.

1. Brand

It is better to go with a highly reputable brand, even if it means spending more on the diamond testers. Presidium is a household name in the jewelry industry for its reliable and accurate diamond testers. The company also offers a wide range of products at different prices.

However, you can also check other well-established brands. Their products are often known for quality and reliability.

2. Price

The prices of diamond testers vary, depending on the functions and features of these products. If you have the budget, go for high-end diamond testers. These are more reliable, accurate, and easy to use. However, a high price tag does not always mean high quality.

3. Ease of Use

This factor is self-explanatory. You don’t want an overly complicated diamond tester that you can’t use well to authenticate your gemstones. Consider the user interface and handling, after which you can choose what meets your needs.

4. Quality and Accuracy

Quality diamond testers are often accurate. And that is what you want to spend your money on. Remember, an inaccurate device can lead to the loss of millions if it wrongly identifies moissanite as diamond or vice versa. You want a diamond tester that gives consistent results.

5. Power Source

Most diamond testers are battery-powered, but some get their power from a USB source. The former option is ideal if you want a portable device you can carry with you. Otherwise, consider a USB-powered diamond tester would be feasible.

6. Conductivity

Diamond testers are either heat or electric devices. So, which of these two is the best choice? Thermal diamond testers are ideal if you are working with a tight budget. They are more affordable. However, if accuracy is everything you need, consider electric diamond testers but be prepared to pay more.


What is a diamond tester?

As the name implies, a diamond tester is a device for authenticating diamonds, but some can also test other gemstones. These devices can use heat or electricity to determine whether the stone under test is a genuine diamond or not. They rely on different thermal and electrical conductivity materials to distinguish diamonds from fakes or simulants.

Do diamond testers only work on diamonds?

No. Some diamond testers can authenticate several gemstones. A high-end device should distinguish genuine diamonds and other gemstones while rejecting simulants. However, some synthetic stones, such as moissanite, can pass a standard tester as natural diamonds.

What are the results of a diamond tester?

This depends on the type of diamond tester you use. Many devices with LEDs will light up different LEDs and produce audible beeps to show test results. By interpreting the illuminated LEDs, you can know if the tested gemstone is diamond or other stimulants.

What stones will pass a diamond tester?

Most diamond testers will give positive results if the stone tested is a genuine diamond or moissanite. However, only synthetic moissanite made before the 1990s would pass the test. Anything newer with a positive result is a natural diamond.

Conclusion: Top 3 Recommendations

Besides jewelers loupes, diamond tester is also an important equipment to have for jewelers. It detects authenticity in no time. The above 10 diamond testers are choices that you can spend more time to make some further researches. However, if you want us to narrow down to 3 choices, then these are:

Choose Presidium Adamas Diamond and Moissanite Tester (B00QDHPNEC) if you have the budget or a jewel dealer. This high-end electrical diamond tester is highly accurate, quick, and reliable and has many remarkable features and functions. It is the ultimate device to consider.

Presidium Instruments Gem Tester II (B000TD3G8Q) is another suitable option for professionals. This mid-range electrical diamond detector can authenticate polished or unpolished gemstones with accurate and consistent results. It can identify up to 16 different stones, including smaller pieces.

HDE Diamond Tester Pen (B009H4WGWK) is the most affordable option for professionals and jewel enthusiasts. This cost-effective device can help you identify genuine products and not waste your hard-earned money. It is also very portable and reliable.

But if these recommendations do not meet your needs, use the buying guide to make the best decision.

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