Moissanite and laboratory-grown diamonds are both created by people, which is why they are often confused. The difference is fundamental: a laboratory-grown diamond is diamond; moissanite is a different gemstone.
What they share
- Both are created under controlled conditions.
- Both are very hard and suit everyday jewelry.
- Both must be described clearly for what they are.
Where they differ
| Moissanite | Laboratory-grown diamond | |
|---|---|---|
| Material | Silicon carbide | Diamond (carbon) |
| Hardness (Mohs) | About 9.25 | 10 |
| Sparkle | Strong rainbow fire | Diamond's balance of brilliance and fire |
| Grading | Producer grades | 4Cs by independent laboratories |
| Price for the same size | Usually lower | Usually higher than moissanite, lower than natural diamond |
How to decide
If you want a diamond, and the independent grading that comes with it, but with a more accessible price than a natural stone, a laboratory-grown diamond is the natural choice. If you are drawn to vivid fire and want the most size for your budget, moissanite is worth considering. Ask to see both in the same light if you can: the difference in character is easier to see than to describe.
Brilliance, fire and scintillation
Three effects make a gemstone sparkle. Brilliance is the white light returned to the eye; fire is the spectral colour produced as light disperses; scintillation is the play of flashes as the stone or the viewer moves. Moissanite has a higher refractive index and more than twice the dispersion of diamond, so it shows more fire. A well-cut laboratory-grown diamond has diamond's balance of brilliance and fire, which many people describe as calmer and crisper.
Durability
Both are excellent for everyday jewelry. The laboratory-grown diamond is harder, at 10 on the Mohs scale, against about 9.25 for moissanite. In daily life both resist scratches very well, and both can chip if struck hard at a vulnerable point, so settings that protect edges and points are worth considering.
Documentation
Laboratory-grown diamonds of significant size are commonly graded by independent laboratories, which issue reports and often inscribe the girdle. Moissanite is usually described by its producer's grades; there is no universal independent grading scale comparable to the diamond 4Cs. If documentation matters to you, it is a real point of difference.
Common misconceptions
- "Moissanite is a type of lab diamond." It is not: it is silicon carbide.
- "Lab-grown diamonds are not real diamonds." They are diamond, with a different origin.
- "You can't tell them apart." Experts often can, by the fire and by double refraction, and instruments always can.
Making the choice
Ask yourself three questions: do you want the material to be diamond; how much does independent grading matter; and which look do you prefer in the light where you will wear it most. The answers usually point clearly in one direction.
Sources: Gemological Institute of America (gia.edu), gem encyclopedia and identification notes on synthetic moissanite; Gemological Institute of America (gia.edu), resources on laboratory-grown diamonds.
Frequently asked questions
Is a lab-grown diamond a type of moissanite?
No. A laboratory-grown diamond is diamond (carbon); moissanite is silicon carbide. Both are made in laboratories.
Which is less expensive?
For the same size, moissanite usually costs less than a laboratory-grown diamond.
Which sparkles more, moissanite or lab-grown diamond?
Moissanite shows more fire, the rainbow flashes, because of its higher dispersion. Diamond shows a crisper balance of white brilliance and colour.
Can I get a report for moissanite?
Some producers issue documents describing their moissanite, but there is no independent grading system comparable to the diamond 4Cs.
