10 Best Diamond Testers 2026 in the United States

The SmartPro Aura Diamond Screener is designed to test both mounted jewelry and loose stones, which makes it quite flexible for different needs. Its standout feature is the ability to detect extremely small stones down to 0.002 carats, using automated screening with options for a quick test or a thorough 360-degree detection. This makes it useful for accurately identifying natural diamonds, CVD and HPHT synthetic diamonds, and common simulants like cubic zirconia.

The built-in smartphone and high-quality camera help automate result processing and even offer certification, adding convenience to the testing process. The device is compact and lightweight enough (around 5 kg or 11 pounds) to be moved if needed, though it’s not ultra-portable like a handheld tester. Its low power consumption suggests it can run for longer periods without frequent recharging. It can handle a large batch of stones (up to 576 at once), including those in transparent bags, which is great for busy jewelers or graders.

The device mainly supports colorless to near-colorless stones (D-K), so it may not be ideal for testing diamonds with stronger color grades. The price and complexity might be a consideration for casual or occasional users. The SmartPro Aura is well suited for professionals or serious hobbyists looking for detailed, automated diamond testing with reliable accuracy and efficient workflow.

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.

The tester is simple to operate, featuring a clear analog dial that can differentiate between 16 types of gemstones, including diamonds and moissanites. This ease of use is beneficial for those who may not be very tech-savvy, as it keeps the testing process straightforward.

There are some drawbacks to consider. Despite its user-friendly design, calibration issues can arise during shipping, which may require assistance from the manufacturer. Additionally, the reliance on AA batteries may be seen as a minor inconvenience for some, as it requires regular replacements. While it generally delivers consistent and reliable results, the quality can vary slightly based on calibration and user proficiency. Being aware of this can help manage expectations.

The Smart Pro MAX Diamond Tester is a handheld device designed to identify different types of gemstones, including natural diamonds, lab-grown diamonds, moissanite, and cubic zirconia, using a unique dual-technology probe that combines thermal and optical testing in one tip. This 5-in-1 feature makes it versatile and accurate for detecting stones as small as 0.02 carats, which is great if you need detailed analysis on a variety of gems.

The tester is user-friendly, featuring a color touchscreen, multilingual voice guidance, and screen rotation for both left and right-handed users, which helps make the testing process smoother. Its Bluetooth connectivity adds convenience by allowing interaction with an app, potentially providing additional support or logging. Portability is fairly good thanks to its rechargeable battery, making it suitable for professional jewelers or enthusiasts who need a ready-to-use, mobile tester. The device's size is somewhat larger compared to simpler testers, which might be less comfortable for some users to carry around all day.

This tester stands out for its advanced, all-in-one detection capabilities and user-friendly design, making it a strong choice if accuracy and versatility across multiple stone types are important to you, though it may be a bit bulky for casual or occasional use.