Do Lab Grown Diamonds Test as Real? Yes, Here's the Science

Yes, lab grown diamonds test as real on a standard diamond tester. They are made of crystallized carbon with the same atomic structure as mined diamonds, so a thermal or electrical pen-style tester reads them as diamond every time. That tester is not checking where a stone came from. It only checks whether the material conducts heat and electricity the way diamond does, and a lab grown diamond does, because it is a diamond.

If you have been worried that a lab grown stone might "fail" the little gadget a jeweler waves over a ring, you can stop worrying. The thing that distinguishes lab grown from mined is not whether it is a real diamond. It is the growth process, and you need far more than a handheld pen to see that.

Why a diamond tester says "diamond" for a lab grown stone

A common pen-style diamond tester measures thermal conductivity. Diamond moves heat away faster than almost any other material, including the simulants people worry about, like cubic zirconia or glass. When the probe touches a real diamond, the heat signature spikes and the tester signals "diamond."

A lab grown diamond has the exact same crystal lattice and the same thermal behavior. There is no chemical or structural difference for the tester to catch. So it reads as diamond, not as a fake. Cubic zirconia, on the other hand, conducts heat poorly and gets flagged immediately. That is the real job of the pen: separating diamond from imitations, not separating grown from mined.

Some newer testers also add an electrical conductivity check. That feature exists to catch moissanite, a different gem that can fool a heat-only tester. A lab grown diamond passes the combined heat-and-electrical check too, for the same reason: it is carbon arranged as diamond.

So is a lab grown diamond "fake"?

No. A lab grown diamond is a real diamond. It is not a simulant. Simulants like cubic zirconia and moissanite are different materials that only look similar to the eye. A lab grown diamond is chemically, physically, and optically the same as a mined diamond. The only difference is origin: one grew underground over a very long time, the other grew in a controlled chamber over a few weeks. Both are carbon. Both sparkle the same way because the optical properties are identical.

How gem labs actually tell lab grown from mined

Here is the honest part. A jeweler with a pocket tester cannot tell you whether a diamond is grown or mined. That requires specialized equipment that the major gem laboratories use, and it works by looking at clues left behind by how the diamond formed.

• Growth patterns. Mined diamonds grow in an octahedral pattern over millions of years. Lab grown diamonds, made by HPHT (high pressure, high temperature) or CVD (chemical vapor deposition), show different internal growth structures. Labs view these under cross-polarized light and magnification.
• Fluorescence and phosphorescence. Under specialized UV imaging, lab grown diamonds often show distinctive fluorescence patterns that differ from natural stones. Some HPHT-grown diamonds glow for a moment after the light is removed, which natural diamonds rarely do.
• Trace elements and inclusions. Natural diamonds carry tiny mineral inclusions from the earth. Lab grown diamonds may carry trace metallic flux (from HPHT) or have a cleaner internal profile. These signatures are read with spectroscopy.
• Laser inscriptions. Most certified lab grown diamonds carry a microscopic inscription on the girdle, readable under magnification, that ties the stone to its certificate and often states "lab grown."

The takeaway: the difference is real and detectable, but only with lab-grade instruments. To the eye, to a jeweler's loupe, and to a handheld tester, a lab grown diamond is indistinguishable from a mined one because there is nothing visually different to find.

What an IGI certificate confirms

This is where you get certainty in writing. Every diamond worth buying should come with an independent grading report. At Diyona, our lab grown diamonds are certified by IGI (and the same standards apply at GIA). A certificate does two important things.

First, it states the origin clearly. A lab grown diamond report says "Laboratory-Grown Diamond" right on the document, along with the growth method where applicable. There is no ambiguity and nobody is hiding the origin. Honesty about origin is the whole point of certification.

Second, it grades the stone on the same scale as any diamond: the 4Cs. Carat weight, cut, color, and clarity are measured by the same trained graders using the same equipment they use for mined stones. If you want a refresher on what those grades mean and how they affect sparkle and price, our 4Cs guide walks through each one in plain language.

So when you buy a certified lab grown diamond, you are not taking anyone's word for it. An independent lab has already confirmed both that it is a real diamond and that it is lab grown, and it has documented exactly how good the stone is.

What this means for buying

Because lab grown and mined diamonds are the same material, you get identical brilliance, hardness (10 on the Mohs scale), and durability. What changes is the price. Lab grown diamonds typically cost about 40-70% less than a comparable mined diamond, which means you can choose a larger or higher-quality stone for the same budget. You can compare certified stones by the 4Cs directly in our diamond search and see how grade shifts price.

A few honest details so there are no surprises. Lab grown diamonds generally have lower resale value than mined diamonds, the same way a new car drops in value after purchase, so buy one because you love it, not as an investment. Our diamonds are made to order, we offer a 30-day return window, and our lifetime warranty covers manufacturing defects (resizing is a paid service, not free). We are online only, so there are no showroom visits or appointments. Everything happens on the site, with certification documents available for every stone.

If you want the full background on how these diamonds are grown and graded, our lab grown diamonds overview covers the HPHT and CVD methods in more depth.

Frequently asked questions

Will a lab grown diamond pass a diamond tester at a jewelry store?

Yes. A standard thermal or electrical diamond tester reads a lab grown diamond as diamond because it is pure carbon with the same conductivity as a mined diamond. The tester is designed to catch fakes like cubic zirconia, and a lab grown diamond is not a fake.

Can a jeweler tell my diamond is lab grown just by looking?

No. A jeweler using a loupe or a handheld tester cannot distinguish lab grown from mined, because the two are optically and chemically identical. Only a gem laboratory with specialized equipment can identify the growth origin, and the result is recorded on the IGI or GIA certificate.

Are lab grown diamonds considered real diamonds?

Yes. Lab grown diamonds are real diamonds, recognized as such by gem laboratories and certified on the same 4Cs scale as mined diamonds. They are not simulants like cubic zirconia or moissanite, which are different materials entirely.

Ready to see certified, real lab grown diamonds graded on the same scale as mined stones? Start with our diamond search to compare options by cut, color, clarity, and carat, then build the ring around the stone you love.