10 Best Diamond Testers 2026 in the United States
#1
Winner
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.
Rating
10.0
Chosen by1,159
Testing Method
Accuracy
Portability
Most important from
1344 reviews
#2
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.
Rating
9.7
Testing Method
Accuracy
Ease of Use
Most important from
8197 reviews
#3
Presidium Instruments Gem Indicator (PGI) Handheld Tester for Identifying Diamonds and Common Colored Gemstones
The Presidium Gem Indicator (PGI) is a handheld diamond tester designed to identify diamonds and a wide range of colored gemstones quickly, usually within 6 seconds. Its standout feature is a retractable, thin probe tip that maintains consistent pressure on stones, helping to improve accuracy. It supports testing up to 31 types of gemstones, which is quite versatile compared to many testers that focus only on diamonds.
Rating
9.4
Testing Method
Accuracy
Ease of Use
Most important from
58 reviews
Top 10 Best Diamond Testers 2026 in the United States
#1
Winner
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) with Assisted Thermal Calibration (ATC) for Identifying Diamonds/Moissanites and Common Colored Gemstones
Testing Method: Thermoelectric probe
Accuracy: Assisted Thermal Calibration
Ease of Use: Simple to operate, clear dial
Portability: Compact and portable
Additional Features: Differentiates 16 types of gemstones
Chosen by 1159 this week
HMKIS Diamond Tester Pen, Professional Jewelry Diamond Tester with 60X Jewelry Loupe Magnifier, Diamond Selector for Novice and Expert (Non-Rechargeable)
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
Presidium Instruments Gem Indicator (PGI) Handheld Tester for Identifying Diamonds and Common Colored Gemstones
Presidium Instruments Gem Indicator (PGI) Handheld Tester for Identifying Diamonds and Common Colored Gemstones
Testing Method: Handheld diamond tester with thin probe
Accuracy: Depends on stone and user technique
Ease of Use: Ergonomic design, digital LED screen
Portability: Lightweight, handheld, USB powered
Battery Life: Decent, limited details
Additional Features: Tests 31 gemstone types, retractable tip
SAM by Presidium, Diamond Tester and Identify a Wider Range of Moissanites
SAM by Presidium, Diamond Tester and Identify a Wider Range of Moissanites
Testing Method: Thermoelectrical probe
Accuracy: Identifies gemstones from 0.01 to 10 carats
Ease of Use: LED display, user-friendly
Portability: Lightweight, compact (6.69 x 1.2 x 1.1 inches)
Battery Life: Approximately 2,000 continuous tests
Additional Features: Advanced algorithm, USB or 3 AAA batteries
PRESIDIUM DIAMONDMATE-C ELECTRONIC DIAMOND TESTER
PRESIDIUM DIAMONDMATE-C ELECTRONIC DIAMOND TESTER
Testing Method: Electronic
Accuracy: Good
Ease of Use: Minimal setup
Portability: 3.4 x 2.4 x 7.5 in
Battery Life: Decent
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Diamond Tester Jewelry Gem Stone Tester Kit – Professional 2-in-1 Tester for Diamonds, Moissanite, Metals, and Gemstones
Diamond Tester Jewelry Gem Stone Tester Kit – Professional 2-in-1 Tester for Diamonds, Moissanite, Metals, and Gemstones
Testing Method: fine, elastic-tipped probe
Accuracy: accurate for stones as small as 2 pt
Ease of Use: user-friendly
Additional Features: metal detector, 25s warm-up, audible alerts
Diamond Tester,High Accuracy Jewelry Diamond Tester Professional Diamond Tester Pen Jeweler Tool for Novice and Expert - Diamond Selector II 9V Battery Included(Black Diamond Testers)
Diamond Tester,High Accuracy Jewelry Diamond Tester Professional Diamond Tester Pen Jeweler Tool for Novice and Expert - Diamond Selector II 9V Battery Included(Black Diamond Testers)
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
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
DiamondNite Dual Tester Jewelry tool
DiamondNite Dual Tester Jewelry tool
Testing Method: dual testing method
Ease of Use: user-friendly operation
Portability: lightweight, weighs under 6 ounces
Battery Life: lasts for multiple tests before recharge
#10
Diamond Tester,Jewelry Diamond Tester Pen+200g/0.01g Mini Jewelry Scale＋60X Mini LED Magnifying, Professional Diamond Selector for Novice and Expert,Thermal Conductivity Meter(Diamond Tester +)
Diamond Tester,Jewelry Diamond Tester Pen+200g/0.01g Mini Jewelry Scale＋60X Mini LED Magnifying, Professional Diamond Selector for Novice and Expert,Thermal Conductivity Meter(Diamond Tester +)
Testing Method: thermal conductivity
Accuracy: quite accurate if used properly
Ease of Use: requires care and reading instructions
Portability: lightweight and portable
Battery Life: 1 9V battery included
Additional Features: mini scale, 60X magnifier, signals
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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.