Will a Diamond Tester Work on Lab-Grown Diamonds?

If you are buying, selling, or already own a lab-grown diamond, one common question is, "Will a diamond tester work on lab-grown diamonds?"

The answer is yes. A genuine lab-grown diamond will normally register as a diamond on a standard diamond tester. However, there is an important limitation: most basic diamond testers cannot tell whether the diamond is natural or lab-grown.

Lab-grown diamonds and natural diamonds have essentially the same chemical composition and crystal structure. Because many handheld testers identify a stone by its physical properties, both types of diamonds can produce a positive diamond result. This is why a diamond tester is useful for initial screening, but it is not usually enough to determine a diamond's origin.

In this guide, we explain how diamond testers work, whether CVD and HPHT diamonds pass a diamond test, how testers compare with moissanite testers, and the best ways to confirm whether a diamond is natural or laboratory-grown.

Does a Diamond Tester Work on Lab-Grown Diamonds?

Yes, a diamond tester works on lab-grown diamonds.

If you place a genuine lab-grown diamond under a standard thermal diamond tester, it will generally register as diamond. The tester responds to the stone's physical properties rather than where the diamond was created.

Natural and lab-grown diamonds share essentially the same thermal conductivity, which is why a traditional thermal tester generally identifies both as diamond.

So, if you are asking:

• Will a diamond tester work on lab-grown diamonds? — Yes.
• Does a diamond tester work on lab diamonds? — Yes.
• Do lab diamonds work on a diamond tester? — Yes.
• Will a lab-grown diamond test positive on a diamond tester? — Usually, yes.

But a positive result does not automatically mean the diamond is natural.

Why Do Lab-Grown Diamonds Test as Real Diamonds?

Lab-grown diamonds are real diamonds. They are created using technology that reproduces the conditions necessary for carbon to crystallize into diamond.

The two primary methods used to create gem-quality lab diamonds are

HPHT Diamonds

HPHT stands for High Pressure, High Temperature. This process uses extremely high pressure and heat to grow a diamond crystal.

CVD Diamonds

CVD stands for Chemical Vapor Deposition. In this process, carbon-containing gases are used to grow diamond crystal layers on a diamond substrate.

Despite their different growth environments, both HPHT and CVD diamonds have the fundamental properties of diamond. GIA notes that laboratory-grown diamonds can have essentially the same chemical composition and crystal structure as natural diamonds.

That is why a basic diamond tester generally cannot determine where the diamond came from.

How Does a Diamond Tester Work?

Most traditional handheld diamond testers work by measuring thermal conductivity.

Diamonds conduct heat extremely efficiently. When the tester's probe touches the gemstone, the device measures how heat moves through the stone.

If the stone has thermal properties associated with diamond, the tester indicates a positive diamond result.

Because both natural and lab-grown diamonds have very similar thermal conductivity, a thermal tester generally cannot distinguish between them.

A Simple Example

Imagine testing these three stones:

The exact result can vary depending on the tester and the condition of the stone, but the important point is that a standard tester is designed to identify diamond-like thermal properties, not diamond origin.

Can a Diamond Tester Tell the Difference Between Lab-Grown and Natural Diamonds?

Most Standard Diamond Testers Cannot.

A traditional handheld tester may tell you that the stone is a diamond, but it usually cannot answer the next question:

Is this diamond natural or lab-grown?

According to GIA, traditional gemological observations and older diamond detectors are generally not sufficient to reliably separate natural diamonds from laboratory-grown diamonds. More advanced equipment or laboratory testing is required for definitive identification.

This is one of the most important things buyers should understand when using a diamond tester.

A Positive Diamond Test Does Not Mean Natural Diamond

If your tester says:

"Diamond"

It may be:

• A natural diamond
• A lab-grown HPHT diamond
• A lab-grown CVD diamond

Therefore, you should not use a basic diamond tester alone to verify that a stone is natural.

Does a Diamond Tester Work on CVD Lab Diamonds?

Yes.

A genuine CVD lab-grown diamond will generally test as a diamond on a standard diamond tester.

CVD diamonds are made by depositing carbon onto a diamond substrate, allowing the diamond crystal to grow. Although the growth process differs from natural diamond formation, the finished gem still possesses the fundamental characteristics of diamond.

Therefore:

CVD lab diamond + standard diamond tester = usually a positive diamond result.

However, the tester generally will not identify the stone specifically as CVD-grown.

Does a Diamond Tester Work on HPHT Lab Diamonds?

Yes.

HPHT-grown diamonds also generally test as diamonds.

The HPHT process creates diamond crystals under high-pressure and high-temperature conditions. The resulting gem-quality diamond shares essential physical and optical properties with natural diamonds.

So, a standard diamond tester will generally indicate that an HPHT-grown diamond is a diamond.

Again, the tester usually cannot tell you whether the diamond is:

• Natural
• HPHT lab-grown
• CVD lab-grown

What About a Diamond and Moissanite Tester?

This is where things can become slightly more complicated.

Some testers are designed as diamond/moissanite testers. These devices may use a combination of thermal and electrical conductivity testing to help distinguish diamond from moissanite.

A basic thermal tester alone may sometimes struggle with moissanite because moissanite also conducts heat efficiently. A tester designed specifically to separate diamond and moissanite can provide more useful screening.

Know about is moissanite a lab grown diamond?

However, a diamond/moissanite tester is still not necessarily designed to tell you whether a diamond is natural or lab-grown.

So the result may look like this:

The capabilities depend on the specific tester, so always check the manufacturer's instructions and limitations.

Can a Jeweler Tell if a Diamond Is Lab-Grown?

Sometimes, but not always through a simple handheld tester.

Trained gemologists may observe certain characteristics that suggest a laboratory-grown origin. However, modern lab-grown diamonds can be difficult to distinguish from natural diamonds, especially with basic equipment.

Professional identification may involve advanced testing methods such as:

• Spectroscopy
• Fluorescence imaging
• Photoluminescence analysis
• Advanced diamond screening instruments

GIA uses specialized technology to identify natural, laboratory-grown, and simulated diamonds. Its iD100 device, for example, is designed to distinguish simulated and laboratory-grown diamonds from natural diamonds within its stated testing scope.

What Is the Best Way to Tell if a Diamond Is Lab-Grown?

The most reliable option is to check the diamond's grading report and, when necessary, have the stone examined by a reputable gemological laboratory.

A laboratory-grown diamond may come with a grading report that identifies it as laboratory-grown and provides information about its characteristics.

You can also check for a laser inscription on the diamond's girdle when applicable. GIA states that its laboratory-grown diamond reports include identification measures such as a laser inscription indicating the diamond is laboratory-grown.

For complete verification, professional laboratory testing is more reliable than relying solely on a basic handheld diamond tester.

Diamond Tester vs. Professional Diamond Testing

Here is the main difference:

A standard tester is useful for quick screening, but it should not be treated as final proof of a diamond's origin. GIA specifically notes that advanced testing or laboratory examination may be necessary for definitive identification.

Can You Test a Lab-Grown Diamond at Home?

Yes, you can use a diamond tester at home to check whether the stone responds like a diamond.

However, there are a few things to remember.

1. Clean the Diamond First

Oil, dirt, or residue may affect the contact between the tester and the stone.

2. Follow the Tester Instructions

Different devices have different requirements. Some work best with loose stones, while others can test mounted diamonds.

3. Test More Than Once

Take multiple readings if you receive an inconsistent result.

4. Understand the Limitation

A positive result usually means the stone has diamond-like properties, but it does not necessarily prove whether the diamond is natural or laboratory-grown.

Can a Lab Diamond Fail a Diamond Test?

A genuine lab-grown diamond should generally test as a diamond when the correct type of tester is used properly.

However, an incorrect or inconsistent result can sometimes happen because of factors such as

• A dirty stone
• Poor probe contact
• A low battery
• An unsuitable testing method
• Very small diamond size
• Certain jewelry settings interfering with the test
• A tester with limited capabilities

If you receive an unexpected result, clean the diamond and follow the manufacturer's testing instructions before drawing a conclusion.

For valuable jewelry, professional testing is the safest option.

Are Lab-Grown Diamonds Fake Because They Test Like Diamonds?

No. A lab-grown diamond is not fake simply because it tests as a diamond.

A genuine lab-grown diamond is a diamond. The main difference is its origin:

• A natural diamond formed through geological processes within the Earth.
• A lab-grown diamond was created in a controlled environment using diamond-growing technology.

GIA explains that laboratory-grown diamonds are essentially chemically and optically the same as natural diamonds, which is why traditional testing cannot reliably separate them.

This is different from diamond simulants such as cubic zirconia and moissanite, which may resemble diamonds but are different materials.

What Should You Ask Before Buying a Lab-Grown Diamond?

A diamond tester is helpful, but it should not be the only factor you consider when buying a diamond.

Ask for:

A Diamond Grading Report

Look for documentation from a recognized gemological laboratory.

The Diamond's 4Cs

Review:

• Cut
• Color
• Clarity
• Carat weight

Growth Method

If available, ask whether the diamond was grown using:

• HPHT
• CVD

Any Post-Growth Treatment

Some lab-grown diamonds may undergo treatment to improve their color or appearance. Professional documentation can provide important information about the diamond.

Seller Disclosure

The seller should clearly disclose whether the diamond is natural or laboratory-grown.

At KRK Jewels, customers can explore lab-grown diamond jewelry with detailed product information and choose designs based on their preferred diamond shape, carat weight, setting, and metal.

Explore Our Collection

Does a Diamond Tester Work on Lab-Grown Diamond Jewelry?

Yes, but testing mounted jewelry requires additional care.

If the diamond is set in a ring, necklace, or earring, make sure the tester probe touches the diamond itself rather than the metal setting.

Small accent diamonds can also be more difficult to test accurately because of their size and position.

For engagement rings and other fine jewelry containing multiple stones, a professional jeweler may be better equipped to test individual diamonds accurately.

Conclusion

So, will a diamond tester work on lab-grown diamonds? Absolutely.

A genuine lab-grown diamond will generally test as a diamond because it has the fundamental properties of a diamond. The important thing to understand is that most standard diamond testers cannot tell the difference between a natural diamond and a lab-grown diamond.

If your goal is simply to determine whether a stone behaves like a diamond, a standard tester can be useful. But if you want to know whether a diamond is natural, CVD-grown, or HPHT-grown, you need advanced screening technology or professional laboratory testing.

When buying a lab-grown diamond engagement ring or other fine jewelry, the best approach is to choose a reputable seller, review the diamond documentation, and understand exactly what you are purchasing. That way, you can enjoy the beauty and brilliance of your diamond with confidence.