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10 Best Diamond Testers 2025 in the United States

#1

Winner

9.8 score

HMKIS Diamond Tester Pen, Professional Jewelry Diamond Tester with 60X Jewelry Loupe Magnifier, Diamond Selector for Novice and Expert (Non-Rechargeable)

The HMKIS Diamond Tester Pen is designed for both novices and experts who need to verify the authenticity of diamonds quickly and accurately. One of its standout features is the dual power supply option, allowing users to choose between a Type-C or a 9V power source, which enhances accuracy and stability. The tool is user-friendly, requiring no professional knowledge to operate; users simply select the diamond size and place the tester on the gemstone. The audible signals and LED indicators make interpreting results straightforward, which is great for anyone needing quick assessments.

Customer Highlights

A summary of real customer reviews to highlight what shoppers are saying!
Testing Method
Differentiating between real diamonds, moissanite, and CZ is a breeze with this tester.
Accuracy
The pen is incredibly easy to use, providing quick and accurate readings.
Ease of Use
The pen is incredibly easy to use, providing quick and accurate readings.
Portability
It's portable and fits comfortably in the hand, making it perfect for on-the-go testing.
Additional Features
The dual power supply option, including a plug-in feature, is a great addition.
#2
9.6 score

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

The Presidium Instruments Gem Tester II (PGT II) is a solid choice for anyone needing a reliable diamond tester, particularly hobbyists and professionals in the jewelry field. One of its standout features is the Assisted Thermal Calibration (ATC), which allows users to calibrate the device easily to their environment, enhancing accuracy in testing. This model is designed to be compact and portable, making it easy to transport, which is a significant advantage for gemologists on the go or those attending trade shows.

Customer Highlights

A summary of real customer reviews to highlight what shoppers are saying!
Testing Method
This machine tests thermal conductivity, offering a reliable method to distinguish glass from precious stones.
Accuracy
Once calibrated, the device works well and easily determines if stones are glass.
Portability
The Presidium Instruments Gem Tester II is portable and customer-displayable, making it convenient for on-the-go gemologists.
#3
9.3 score

High Accuracy Professional Diamond Tester Pen Jeweler Tool for Novice and Expert - Diamond Selector II 9V Battery Included(Black)

The Hqdz Diamond Selector II is a professional diamond tester pen suitable for both novices and experts. It uses thermal conductivity to distinguish genuine diamonds from fake ones, ensuring high accuracy in testing. The device features an LCD display, LED indicators, and emits audible sounds to differentiate readings, making it user-friendly. However, it requires operation with bare hands and two-hand usage, which might be inconvenient for some users.

Customer Highlights

A summary of real customer reviews to highlight what shoppers are saying!
Accuracy
The diamond tester works well, even with small diamonds, and comes with a 9V battery and a protective carrying case.
Ease of Use
Instructions could be clearer, especially about the protective cap over the end of the tester, which is not immediately obvious.
Portability
Lightweight and not very bulky, the tester features a protective cap for the probe and a bright screen for easy readability.
Additional Features
The diamond tester works well, even with small diamonds, and comes with a 9V battery and a protective carrying case.

Top 10 Best Diamond Testers 2025 in the United States

#1

Winner

9.8 score

HMKIS Diamond Tester Pen, Professional Jewelry Diamond Tester with 60X Jewelry Loupe Magnifier, Diamond Selector for Novice and Expert (Non-Rechargeable)

Testing Method: Select diamond size, place tester
Accuracy: Enhanced accuracy, dual power supply
Ease of Use: User-friendly, no professional knowledge
Portability: Lightweight (120 grams), compact
Additional Features: 60X LED Loupe, dual power supply

Chosen by 1134 this week

High Accuracy Professional Diamond Tester Pen Jeweler Tool for Novice and Expert - Diamond Selector II 9V Battery Included(Black)

Testing Method: Thermal conductivity
Accuracy: High
Ease of Use: User-friendly
Portability: Lightweight, leather pouch case
Battery Life: Standard 9V battery
Additional Features: LCD display, LED indicators, audible sounds

PDMT-A Diamond Mate Electronic Tester A

Testing Method: Thermal Conductivity
Accuracy: Metal detector avoids false readings
Ease of Use: User-friendly
Portability: Weighs 0.4 pounds, portable
Battery Life: Low power usage, battery indicator
Additional Features: Instant recovery, metal detector, warranty
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Buying Guide for the Best Diamond Testers

Choosing the right diamond tester can be a crucial decision, especially if you are in the business of buying or selling diamonds, or if you simply want to ensure the authenticity of your precious stones. A diamond tester is a device that helps you determine whether a stone is a real diamond or a simulant. To make an informed decision, you need to understand the key specifications and features of diamond testers. This guide will help you navigate through the important aspects to consider when selecting a diamond tester that best fits your needs.
Testing MethodThe testing method refers to how the diamond tester determines the authenticity of a diamond. There are two main types: thermal conductivity testers and electrical conductivity testers. Thermal testers measure how well the stone conducts heat, while electrical testers measure how well it conducts electricity. Thermal testers are generally good for distinguishing diamonds from other stones like cubic zirconia, but they may not be as effective with synthetic diamonds. Electrical testers can identify synthetic diamonds but may give false positives with moissanite. Choose a tester based on the types of stones you most frequently encounter.
AccuracyAccuracy is crucial when it comes to diamond testing, as you want to be sure of the results. Higher accuracy testers will provide more reliable results, reducing the risk of false positives or negatives. Accuracy can be influenced by the quality of the tester and the technology it uses. For professional use, opt for a tester with high accuracy to ensure you are making informed decisions. For personal use, a moderately accurate tester may suffice, especially if you are not dealing with high volumes of stones.
Ease of UseEase of use refers to how user-friendly the diamond tester is. Some testers come with simple interfaces and clear instructions, making them easy to operate even for beginners. Others may have more complex features that require a bit of learning. If you are new to diamond testing, look for a tester that is straightforward and easy to use. If you are more experienced, you might prefer a tester with advanced features that offer more detailed analysis.
PortabilityPortability is an important factor if you need to test diamonds on the go. Portable diamond testers are usually compact and lightweight, making them easy to carry around. They often run on batteries, so you don't need to worry about finding a power source. If you frequently travel or need to test diamonds in different locations, a portable tester is a good choice. For stationary use, a larger, more robust tester might be more suitable.
Battery LifeBattery life is a consideration if you opt for a portable diamond tester. A tester with a long battery life will allow you to perform multiple tests without needing to recharge or replace the batteries frequently. This is especially important if you are using the tester in a professional setting where you might need to test many stones in a day. Look for testers with rechargeable batteries or those that use standard batteries that are easy to replace.
Additional FeaturesSome diamond testers come with additional features that can enhance their functionality. These may include built-in UV lights for fluorescence testing, multiple testing modes, or the ability to test other gemstones. While these features can be useful, they may also add to the complexity and cost of the tester. Consider whether these additional features are necessary for your needs or if a simpler model will suffice.

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