With the rise of lab-grown diamonds and simulant stones such as Moissanite and CZ, distinguishing them with the naked eye has become increasingly difficult. Therefore, diamond testers and specialized testing devices have become indispensable tools for jewelry stores and gemological centers. In this article, PMAC provides comprehensive information on how these devices work, the most common types available, and guidance to help you choose a reliable and suitable diamond testing tool.
I. Introduction
1. What is a diamond testing device?
A diamond tester (also called a diamond measuring device or diamond checking machine) is a specialized tool used to determine the authenticity of diamonds, distinguish between natural and lab-grown diamonds (CVD/HPHT), and identify simulant stones such as Moissanite or CZ.
Figure 1: Tester for simulated gemstones such as Moissanite and CZ
Diamond testers are widely used in:
– Jewelry stores and gold shops
– Gemological laboratories
– Diamond trading businesses
– Individuals buying or selling diamonds who need to verify quality
With their fast classification capability, diamond testers help minimize risks and provide high reliability in diamond transactions.
2. How diamond testers work and how to use them
Diamond testers operate based on specialized technologies that analyze the unique properties of diamonds, including:
Thermal conductivity measurement: Real diamonds conduct heat extremely well. The tester emits a small thermal pulse onto the surface of the stone and measures the heat dissipation rate to determine authenticity.
Electrical conductivity measurement: Some testers use electrical sensors to differentiate natural diamonds, lab-grown diamonds, and moissanite based on their varying conductivity.
Optical analysis (spectroscopy – fluorescence): The device shines a specialized light onto the stone and analyzes the reflected light to examine the crystal structure, distinguishing natural diamonds from CVD and HPHT lab-grown diamonds.
AI recognition: High-end models use multispectral cameras combined with AI to analyze images, enhancing accuracy in diamond identification.
II. Common types of diamond testing devices
1. Professional desktop diamond testers
For diamond grading experts, professional desktop diamond testers are always the preferred choice. These devices are equipped with advanced technologies such as UV–VIS–IR spectroscopy, X-ray, fluorescence analysis, thermal and electrical conductivity measurement, and AI-based crystal structure recognition. This allows the tester to deliver highly accurate and detailed results, clearly distinguishing natural diamonds, CVD and HPHT lab-grown diamonds, as well as complex simulants like Moissanite, CZ, or synthetic Spinel.
Figure 2: Benchtop diamond testers and handheld diamond testers
Although priced higher than handheld diamond pens, professional desktop testers ensure absolute reliability, making them ideal for gemological laboratories, high-end jewelry stores, and large-scale diamond purchasing and grading operations.
2. Handheld diamond testing pens
Handheld diamond testers are compact, easy-to-use devices that are convenient to carry, making them suitable for both individual users and jewelers. These devices primarily operate based on measuring thermal conductivity or electrical conductivity, allowing users to quickly verify the authenticity of a stone. Handheld testers provide instant results and can distinguish diamonds from some common simulants. However, they have certain limitations and cannot accurately differentiate between natural and lab-grown diamonds or high-quality Moissanite.
III. Top 3 most popular diamond testing devices in 2025
1. OGI CS2 diamond tester
The OGI CS2 is one of the most popular professional diamond testing devices today, trusted by jewelry stores and gemological laboratories.
The device utilizes thermal, electrical, and optical measurement technologies to verify the authenticity of diamonds in just a few seconds. The OGI CS2 can accurately distinguish natural diamonds, CVD diamonds, HPHT diamonds, Moissanite, and various simulants. Simply place the diamond into the device, and the result is displayed within seconds, making it easy for users to determine the stone’s authenticity. The machine operates reliably, is user-friendly, and can test both loose diamonds and diamonds set in jewelry, enhancing trust in every transaction.
2. Presidium ARI diamond testing pen
The Presidium ARI diamond tester utilizes advanced Raman spectroscopy technology, providing highly accurate identification.
Thanks to its crystal structure analysis capabilities, the ARI can clearly distinguish natural diamonds, lab-grown diamonds (CVD/HPHT), and high-quality simulants. The device is compact and portable, making it ideal for jewelers, gemological professionals, and jewelry stores that require high accuracy while prioritizing flexibility.
3. Presidium PMUT III diamond testing pen
The Presidium PMUT III is a versatile diamond tester, popular among small jewelry stores and individual users due to its compact size and affordable price.
The device operates based on thermal and electrical conductivity measurements, delivering quick results suitable for distinguishing diamonds from common simulants such as CZ or Moissanite. Its compact design and ability to operate on rechargeable batteries or direct power supply provide flexibility and convenience for users.
Figure 3: Top 3 most popular diamond testing devices in 2025
IV. Reliable Diamond Tester Suppliers in Vietnam
PMAC Joint Stock Company is a leading provider in the supply, distribution, and specialized laboratory (LAB) services for the jewelry industry in Vietnam.
With 5 years of establishment and growth, PMAC brings together a team of highly experienced experts, each with 5 to 20 years of experience in the jewelry sector. This enables PMAC not only to deliver high-quality diamond testing equipment but also to provide technical consulting, machine operation training, and device calibration, helping jewelry stores, gemological centers, and manufacturing facilities enhance accuracy and efficiency in diamond testing.
When purchasing diamond testing machines from PMAC, customers enjoy the following privileges:
– Guaranteed genuine products with a complete 9-step European-standard jewelry process.
– Expert guidance and support for machine operation from highly specialized technical professionals, ensuring efficient and precise use.
– A dedicated consulting team available 24/7, providing quick and precise answers to all customer inquiries.
Conclusion
Diamond testing machines and specialized inspection devices are essential tools for quickly and accurately distinguishing between natural diamonds, synthetic diamonds, and simulant stones. From professional desktop machines like the OGI CS2 to handheld testers such as the Presidium ARI and PMUT III, each device has its own advantages and limitations, suitable for different usage needs. In Vietnam, PMAC is a leading provider of genuine diamond testing equipment, offering expert technical services, 24/7 training and consultation, and serving as a trusted partner for jewelry stores, gemological centers, and professional jewelers.
If you are looking for an effective diamond testing solution, let PMAC be your trusted partner!
PMAC Joint Stock Company
HCM: High-Tech Center, 4th Floor, HUTECH Building, D1 Street, High-Tech Park, Tang Nhon Phu Ward, Ho Chi Minh City
HN: 22B Ơ2 Linh Dam Peninsula, Hoang Liet Ward, Hanoi City
(+84) 938 085 278