Side by side
| Natural | Lab grown | |
|---|---|---|
| Material | Crystalline carbon | Crystalline carbon, identical |
| Mohs hardness | 10 | 10 |
| Refractive index | 2.42 | 2.42 |
| Passes a diamond tester | Yes | Yes |
| Graded on the 4Cs | Yes | Yes, same scales |
| Rough price | Baseline | Commonly 15 to 30 percent of natural |
| Resale value | Poor but non-zero | Very poor and falling |
| Told apart by | Lab equipment only | Lab equipment and girdle inscription |
What people get wrong
The most common misconception is that a lab grown diamond is a simulant, in the same family as cubic zirconia or moissanite. It is not. CZ and moissanite are different materials that resemble diamond. A lab grown diamond is diamond, grown in a machine instead of in the mantle.
Every physical test on this site gives the same result for both. It sinks at 3.52, it clears fog instantly, you cannot read through it, it scratches everything. There is no home test that separates them and there never will be.
The honest case for each
Buy lab grown if you want the largest, cleanest, whitest stone your money will buy and you regard the ring as something to wear rather than an asset. The size difference at a fixed budget is not subtle: the same money commonly buys two to three times the carat weight.
Buy natural if resale or inheritance matters to you, or if the origin story genuinely does. Be clear-eyed that natural resale is also poor, commonly a quarter to a half of retail. The difference is that natural has a floor and lab grown pricing is still falling.
What to check on the certificate
Any lab grown stone of real value should be graded by GIA or IGI and laser inscribed on the girdle with a report number and a note that it is laboratory grown. Check the inscription against the certificate. That inscription is the only practical way you will ever confirm what you own.
Not sure what you are looking at?
Photograph the stone and the app gives you a visual read on the 4Cs, an estimated value range, and what to check next. Free on iOS and Android.
Frequently asked questions
Are lab grown diamonds real diamonds?
Can a jeweller tell the difference?
Do lab grown diamonds hold their value?
How are they made?
Worth being clear: everything here, and the app itself, is an educational reference. At-home tests narrow things down, they do not certify a stone. Before you buy, sell or insure anything of real value, get it looked at by a certified gemologist or an independent appraiser.