How Diamond Testers Work

Unlocking the Mystery of Lab-Grown Diamonds using a tester

The allure of real diamonds has always been captivating, symbolizing everlasting love, beauty, and rarity. However, advancements in technology have introduced lab-grown diamonds, also known as synthetic or cultured diamonds, into the market. These man-made gems possess the same physical and chemical properties as natural diamonds but are created in controlled laboratory environments. 

As lab-grown diamonds become more prevalent, accurate and reliable diamond testing methods have become a must-have to differentiate between natural and lab-grown diamonds. This article will explore the fascinating world of lab-grown diamond testers, their working principles, and the advanced technologies behind them that ensure reliable results.

Understanding Lab-Grown Diamonds

Before diving into the workings of lab-grown diamond testers, it is crucial to understand the basics of lab-grown diamonds and how they differ from real diamonds. Natural diamonds take millions of years to form under the Earth's intense heat and pressure, while lab-grown diamonds are produced through two primary methods: High-Pressure High-Temperature (HPHT) and Chemical Vapor Deposition (CVD). Both methods aim to replicate the natural diamond growth process by providing an environment conducive to diamond crystal formation.

Importance of Using a Lab-Grown Diamond Tester

As lab-grown diamonds become more popular, the need for accurate diamond testing has become a must-have. Differentiating between natural and lab-grown diamonds is essential for several reasons. We outline some of the most important reasons below.  

Ethical and Environmental Concerns

The increasing awareness and concern for ethical and environmental issues have led many consumers to seek eco-friendly and conflict-free options when purchasing diamonds. Lab-grown diamonds offer a way to address these concerns. As mentioned above, lab-grown diamonds have a smaller environmental footprint compared to earth-mined diamonds, as they do not involve destructive mining practices. 

Additionally, lab-grown diamonds are inherently conflict-free, providing buyers with the assurance that their purchase is not supporting unethical practices or contributing to human rights abuses in diamond-producing regions. Knowing the origin of a diamond allows consumers to make informed and conscious decisions aligned with their values.

Economic Implications

Lab-grown diamonds are generally more affordable than natural diamonds. The controlled and efficient process of growing diamonds in a laboratory setting reduces production costs, making lab-grown diamonds a cost-effective alternative. However, for the market to function fairly and transparently, accurate testing methods are essential. 

By using reliable and precise techniques for identifying lab-grown diamonds and distinguishing them from natural diamonds, jewelers can ensure fair pricing and market transparency. This benefits both consumers, who can access high-quality diamonds at competitive prices, and the industry, which can maintain trust and credibility.

Jewelry Integrity

Maintaining jewelry integrity is crucial for jewelers to uphold their reputation and establish trust with their customers. Providing accurate information about the diamonds they sell, including whether they are lab-grown or natural, is a key aspect of jewelry integrity. Jewelers must ensure that their customers have a clear understanding of the product they are purchasing, its characteristics, and its origin. 

By being transparent and honest in their dealings, jewelers can foster long-term relationships with their customers and demonstrate their commitment to ethical business practices. This integrity is especially vital in an industry where trust and authenticity play significant roles in customers' purchasing decisions.

Lab-Grown Diamond Testing Methods

Several methods are employed to distinguish between natural and lab-grown diamonds. Some traditional techniques include visual inspection, loupe examination, UV fluorescence, and thermal conductivity tests. However, some of these methods can be subjective and may not provide reliable results.

Advanced Diamond Testers: A Must-Have in the Market

Modern lab-grown diamond testers are based on advanced scientific principles and high-tech technologies that ensure objective and reliable results. Some of the must-have testing methods include:

Diamond Conductivity Test

The diamond conductivity test is a method used to determine the electrical conductivity of a diamond. It is particularly useful in distinguishing between lab-grown diamonds and natural diamonds, as they often exhibit different electrical properties. Natural diamonds are generally poor conductors of electricity, while lab-grown diamonds may have varying levels of conductivity depending on the specific growth process used.

In the test, a diamond is placed between two electrodes, and a small electric current is passed through it. The electrical conductivity is then measured and compared to known values for natural diamonds. Since lab-grown diamonds are often created using different techniques, their conductivity can deviate from that of natural diamonds.

Thermal Conductivity Test

The thermal conductivity test is another method employed to differentiate between natural and lab-grown diamonds based on their thermal properties. It involves using a small probe or sensor to apply heat to the surface of the diamond. The rate at which the diamond cools down is then measured and analyzed.

Natural diamonds have high thermal conductivity, meaning they can quickly dissipate heat. Lab-grown diamonds, on the other hand, might have lower thermal conductivity due to differences in their crystal structures. By comparing the cooling rates of the diamond being tested with known values of natural diamonds, gemologists can make informed judgments about its origin.

UV-Visible Spectroscopy

UV-visible spectroscopy is an advanced analytical technique used to study the interaction of diamonds with ultraviolet (UV) and visible light. When a diamond is exposed to light, it absorbs certain wavelengths and emits others, creating a unique pattern of absorption and emission known as a “spectral fingerprint.”

By subjecting a diamond to UV and visible light using specialized spectrometers, gemologists can obtain its spectral fingerprint. This fingerprint contains valuable information about the diamond's structure and composition. It serves as a powerful tool for distinguishing between natural and lab-grown diamonds since the two types may exhibit subtle differences in their spectral fingerprints due to variations in their crystal growth environments.

X-Ray Luminescence (XRL)

X-ray luminescence (XRL) is a technique used to examine how diamonds respond to X-rays. When exposed to X-rays, diamonds may emit specific luminescence patterns that can be indicative of their origin. This method is particularly helpful for identifying lab-grown diamonds since they might exhibit distinct luminescence characteristics compared to natural diamonds.

During an XRL test, a diamond is exposed to X-rays, and the emitted light is analyzed using specialized equipment. The resulting luminescence patterns can provide valuable information about the diamond's growth history and potential treatments. By comparing these patterns to a database of known natural and lab-grown diamond luminescence data, gemologists can make accurate determinations about the diamond's authenticity.

Raman Spectroscopy

Raman spectroscopy is a powerful analytical technique used to investigate the vibrational modes of diamond crystals. It involves shining a laser light onto the diamond, and the scattered light is then analyzed to determine the unique Raman spectrum of the diamond.

Each type of diamond, whether natural or lab-grown, has a specific Raman spectrum associated with its crystal structure and composition. By comparing the Raman spectrum of a diamond under analysis with a database of reference data, gemologists can identify the diamond's origin.

Raman spectroscopy is particularly effective in distinguishing between natural and lab-grown diamonds because it can detect subtle differences in their crystal structures. In short, it’s a non-destructive and highly reliable method widely used in gemology and diamond research.

Additional Lab-Grown Diamond Testing Techniques

Apart from the must-have methods, gemologists also use additional techniques to differentiate between natural and lab-grown diamonds. These methods may include:

Moissanite Tester

A moissanite tester is a specialized device used to identify moissanite, a popular diamond simulant, from natural or lab-grown diamonds. Moissanite has different electrical and thermal properties compared to diamonds, making it possible to distinguish between the two.

The moissanite tester typically works by measuring the gem's electrical conductivity or by assessing its thermal conductivity. Moissanite, being a different material from diamonds, will show distinct responses in these tests, allowing gemologists and jewelers to quickly and accurately identify moissanite gemstones.

Pen Tester (Diamond Tester Pen)

A pen tester, also known as a diamond tester pen, is a handheld instrument used to rapidly determine the authenticity of a diamond. The pen tester works based on the principle of electrical conductivity. Diamonds are exceptional electrical insulators, which means they do not conduct electricity well. On the other hand, diamond simulants, such as cubic zirconia or moissanite, often have higher electrical conductivity.

When the pen tester's tip comes into contact with the surface of a gemstone, it measures the gem's ability to conduct electricity. If the gem is a real diamond, the pen tester will not detect any significant electrical conductivity, indicating its authenticity. However, if the gem is a simulant, the pen tester will likely register some level of electrical conductivity, signaling that it is not a genuine diamond.

Gemological Expertise

Gemological expertise refers to the knowledge, skill, and experience possessed by qualified gemologists in evaluating and identifying gemstones, including diamonds. Gemologists are highly trained professionals who have specialized knowledge of gemstone properties, gem formation, and various identification techniques.

Through careful visual inspection and observation using specialized tools, gemologists can identify unique characteristics of diamonds. They examine factors such as the diamond's color, clarity, cut, and carat weight, as well as its optical properties like brilliance, dispersion, and luster. This detailed analysis enables gemologists to determine whether a diamond is natural, lab-grown, or a simulant.

UV Light Testing

UV light testing is a method used to assess the fluorescence of diamonds under ultraviolet light. When exposed to UV light, some diamonds may exhibit fluorescence, emitting visible light in response. The fluorescence color and intensity can vary, providing valuable information for diamond identification.

Natural diamonds and lab-grown diamonds may show different fluorescence patterns, aiding in their differentiation. Additionally, some treatments used on diamonds may affect their fluorescence behavior. Gemologists use specialized UV lamps to conduct this test and examine the diamond's reaction to different wavelengths of ultraviolet light.

Laser Inscription

Laser inscription involves marking a diamond's girdle (the outer edge between the crown and pavilion) with a microscopic laser inscription. This inscription may include information like a certificate number, a logo, or a unique identifier. The purpose of laser inscriptions is to provide an additional means of diamond identification and traceability.

In the case of lab-grown diamonds, the laser inscription may indicate their origin or laboratory-grown status, helping to differentiate them from natural diamonds. This inscription is usually only visible under magnification and does not impact the diamond's appearance or value. Laser inscriptions offer an added layer of security and confidence for consumers, as they can verify the diamond's authenticity and provenance.

Lab-Grown Diamonds: A Recommended Choice

Lab-grown diamonds offer a host of benefits, making them a recommended choice for environmentally conscious buyers. These additional advantages include:


Lab-grown diamonds are considered to have a smaller environmental footprint compared to earth-mined diamonds. The process of mining natural diamonds involves significant environmental disturbances, including habitat destruction, soil erosion, and water pollution. On the other hand, lab-grown diamonds are produced in controlled laboratory settings, using advanced technologies that require fewer resources and have a reduced impact on the environment.


Lab-grown diamonds are inherently conflict-free. One of the major concerns with natural diamonds is the issue of "conflict diamonds" or "blood diamonds," which are diamonds that are mined in war zones and sold to fund armed conflicts, often leading to human rights abuses and environmental devastation. Since lab-grown diamonds are created in controlled environments, there is no possibility of them being associated with conflict or unethical practices.

High Quality

Lab-grown diamonds are manufactured using advanced techniques that allow for precise control over their growth conditions. As a result, lab-grown diamonds can meet the same high-quality standards as natural diamonds. They exhibit the same physical and visual properties as natural diamonds and can be graded by gemological institutions using the same criteria. When properly cut and polished, lab-grown diamonds can be just as brilliant and beautiful as their natural counterparts.

Non-Diamond Options

For buyers seeking alternatives to real diamonds, lab-grown gemstones offer an ethical and affordable choice. Lab-grown white sapphires and cubic zirconia are popular non-diamond options. White sapphires can closely resemble diamonds, with their near-colorless appearance and sparkle. Cubic zirconia, though not as durable as diamonds, can also imitate the look of a diamond and are available at a fraction of the cost.

Near Colorless

Lab-grown diamonds are often available in near-colorless grades, which means they have very little or no detectable color when viewed face-up. The Gemological Institute of America (GIA) grades diamonds on a color scale ranging from D (colorless) to Z (light yellow or brown). Near-colorless diamonds typically fall within the G to J range, and these grades offer excellent visual appeal as they appear bright and clear to the naked eye.

It's worth noting that while lab-grown diamonds are often near-colorless, they can also be found in various color grades, just like natural diamonds. This allows buyers to choose from a wide range of colors depending on their preferences and budget.

The Evolution of Diamond Testing Methods

As the popularity of lab-grown diamonds continues to rise, the demand for accurate and reliable diamond testers has become a must-have in the jewelry industry. By utilizing advanced scientific principles and high-tech technologies, gemologists can effectively differentiate between natural and lab-grown diamonds. Whether you opt for real diamonds or lab-grown diamonds, the key is to make an informed decision that aligns with your preferences and values.