Lab-Grown vs Mined Diamonds: The Numbers That Matter
Both camps in the diamond debate lean on numbers that don't survive a second look. Here are the ones that do — each checkable on a grading report, a spec sheet, or your own receipt.
Numbers that are identical
| Measure | Lab-grown | Mined |
|---|---|---|
| Hardness (Mohs) | 10 | 10 |
| Refractive index | 2.42 | 2.42 |
| Dispersion | 0.044 | 0.044 |
| Density | 3.52 g/cm³ | 3.52 g/cm³ |
These four numbers are why no jeweller's loupe, no dinner guest, and no standard tester can separate the two. Sparkle is physics, and the physics ties.
The number that isn't: price per carat
Like-for-like — same cut grade, colour, clarity — a lab-grown stone typically costs a small fraction of its mined twin, and the gap has widened year over year as growing technology scales. We won't print a percentage here because it moves; instead, run the test yourself: price a 1.5 ct, Excellent-cut, F-colour, VS1 in both columns anywhere reputable. The ratio will make the argument better than we can.
The number everyone misuses: resale
The honest version: most jewelry — mined or grown — resells well below retail. Mined stones hold a resale market with deeper roots; grown stones' secondary market is younger and thinner. If resale drives your decision, buy natural and buy blue-chip. If wearing it forever drives your decision, the resale column matters less than the cut grade.
The numbers on the report
Whatever the origin, the four figures that decide beauty are on the certificate: cut grade, colour, clarity, and the measurements line. A grown F/VS1/Excellent outperforms a mined H/SI2/Very Good on every visible dimension — and vice versa. Origin tells you the story; the report tells you the stone. How to read one →
The bottom line
Buy the certificate, not the slogan. And whichever column you choose, we'll show you the documents first. The full comparison guide →