Yes, lab grown diamonds pass a standard diamond tester, because they are real diamonds with the same chemical makeup and physical properties as natural ones. A handheld tester can tell a diamond from a simulant such as cubic zirconia, but it cannot tell a lab grown diamond from a natural diamond. That needs specialist equipment, usually in a gemmological laboratory.
This question comes up a lot, often from people worried that a lab grown diamond is somehow a fake. It is not, and here is why the tester agrees.
How a diamond tester works
The most common handheld testers measure thermal conductivity, which is how quickly heat moves through a stone. Diamond moves heat very quickly, far faster than glass or cubic zirconia. When the probe touches a diamond, the heat travels away fast and the tester reads it as diamond.
Lab grown diamonds are made of the same carbon crystal structure as natural diamonds, so they conduct heat in the same way. A thermal tester reads both as diamond.
What about moissanite?
Moissanite also conducts heat well, so it can fool a basic thermal tester. Some testers add a second check for electrical conductivity to separate moissanite from diamond. Moissanite is a different material altogether, and our guide to moissanite vs lab grown diamonds explains how they differ in look and wear.
So how do you tell lab grown from natural?
Because the two are the same material, the difference lies in tiny details of how they formed. Gemmological laboratories use specialist instruments to study these growth features and the way the stone responds to particular kinds of light. This is not something a handheld tester or a jeweller's loupe can do reliably.
The practical answer is the grading report. A lab grown diamond graded by GIA or IGI comes with a report that states it is laboratory grown, and the stone is often laser inscribed on its edge with a report number you can match to the paperwork.
Is a lab grown diamond a real diamond?
Yes. It is diamond in every physical and chemical sense. The only difference is its origin: one grew in the earth, the other in a controlled environment. We cover this in more depth in are lab grown diamonds fake?
Why people ask
Often the question comes from someone who has had a ring tested at a shop or with a tester bought online, and wants to know whether the result can be trusted. The tester is doing its job: it is confirming that the stone is diamond. It simply was not built to answer the separate question of where that diamond came from.
What this means when you buy
- A tester confirms that a stone is diamond, not whether it is natural or lab grown.
- The grading report is how you confirm origin, along with the cut, colour, clarity and carat.
- Ask for the report number and check it on the laboratory's own website.
Every lab grown diamond we offer comes with a GIA or IGI report, and every ring is crafted by specialist goldsmiths and UK hallmarked. You can browse our lab grown diamonds, or start a bespoke design with us. Bespoke rings start from £600.
Frequently asked questions
Will a lab grown diamond test as real?
Yes. A standard diamond tester reads a lab grown diamond as diamond, because it is a real diamond.
Can a jeweller tell if a diamond is lab grown just by looking?
Not reliably. Separating lab grown from natural diamonds needs specialist laboratory equipment, which is why the grading report matters.
Can moissanite pass a diamond tester?
It can fool a basic thermal tester. Testers that also check electrical conductivity are designed to separate moissanite from diamond.
How do I know my diamond is lab grown?
Check its GIA or IGI grading report, which states the origin, and match the report number to any laser inscription on the stone.