Do Lab-Grown Diamonds Pass a Diamond Tester?

Yes, and that is exactly what should happen. A basic diamond tester works by measuring how quickly a stone moves heat, and diamond conducts heat better than almost anything else, so the tester lights up for it. A lab-grown diamond is made of the same pure carbon in the same crystal structure as a mined diamond, so it conducts heat identically and reads as diamond. This is not a false positive or a trick, it is the correct result, because a lab-grown diamond genuinely is a diamond. The tester is confirming the material, not the origin. If someone tells you a lab-grown stone failing to register as diamond would prove it is fake, they have it backwards: passing the tester is exactly what a real lab-grown diamond does.

No, a standard tester cannot tell them apart, because there is nothing different for it to measure. A mined diamond and a lab-grown diamond are the same material, so both conduct heat and electricity the same way and both simply read as diamond. Separating natural from lab-grown takes specialised equipment found in gem laboratories, which studies how the crystal grew and how it responds to light to identify the tiny signatures left by each growth process. That is why origin is not something you confirm with a pocket tester, but something you read on the grading report. Reputable labs test for it and print the result clearly, and many stones are also laser-inscribed. If origin matters to you, rely on the report, not a handheld device.

It depends on the tester. Moissanite also conducts heat well, so an older heat-only tester can read it as diamond, which is where the confusion comes from and why some people worry about being fooled. Modern testers solve this by adding an electrical conductivity check, because moissanite conducts electricity differently from diamond. A combined thermal and electrical tester will separate the two clearly, flagging moissanite rather than passing it as diamond. So the honest answer is that moissanite can slip past a cheap pen-style tester but not a proper dual one. When someone tests a stone for you, it is worth asking which type of tester they are using, and any reputable jeweller will be using a dual tester as standard.

Check the grading report, because that is the only reliable way to know. A pocket tester will confirm the stone is a diamond but cannot tell you where it came from, since mined and lab-grown diamonds are the same material. Gem laboratories test each stone's origin and state clearly on the report whether it is natural or laboratory-grown, and many diamonds are laser-inscribed on the girdle with a number that matches the report, so you can confirm the paper belongs to that exact stone. If you have a diamond with no paperwork and you want to know its origin, an independent lab can test it. Bring it to our Coquitlam studio and we will look at any report with you and help arrange lab testing if you need it.

Lab-grown diamonds usually sell for less than mined diamonds of the same grade, often noticeably so, which is a large part of their appeal. Because they can be produced in a controlled setting rather than found, supply is steadier and the price is lower, so the same budget buys a larger or higher-grade stone. Whether that lower price matters to you depends on what you value. Some buyers love getting more diamond for their money and are happy with a lab-grown stone that looks identical to the eye. Others place value on the rarity and long history of a mined diamond and prefer that, even at a premium. Neither choice is wrong. Our lab-grown versus natural guide walks through the trade-offs so you can decide what fits you.