A lab-grown diamond is a diamond; moissanite is not. Moissanite is silicon carbide, a different material used as a diamond simulant, with a hardness of 9¼ against diamond's 10, while a lab-grown diamond has the same crystal structure as a mined diamond. The choice comes down to whether you want a diamond or a diamond look-alike.
Moissanite vs lab-grown diamond: what's the difference?
| Moissanite | Lab-grown diamond | |
|---|---|---|
| What it is | Silicon carbide (a diamond simulant) | Carbon crystallized as diamond |
| Mohs hardness | 9¼ | 10 |
| Refractive index | 2.648 and 2.691 (doubly refractive) | 2.42 |
| Specific gravity | 3.22 | About 3.52 |
Moissanite figures are from GIA's study of near-colorless synthetic moissanite: "With refractive indices of 2.648 and 2.691, a dispersion of 0.104, a hardness of 9¼ on the Mohs scale, and a specific gravity of 3.22, synthetic moissanite is much closer to diamond in overall appearance and heft than any previous diamond imitation." (GIA, Gems & Gemology, Winter 1997) Diamond figures are from the FTC's definition: "Its hardness is 10; its specific gravity is approximately 3.52; and it has a refractive index of 2.42." (16 CFR 23.12)
Is moissanite a real diamond?
No. GIA lists moissanite with glass and cubic zirconia as a common simulant, "completely unrelated to diamonds at the atomic level." A lab-grown diamond, by contrast, has "the same crystal structure, consisting of tightly bonded carbon atoms" as a mined diamond (GIA, Simulants, Moissanite and Lab-Grown Diamonds). That is also why the law treats them differently: a lab-grown stone may use the word "diamond" with a "laboratory-grown" qualifier, while a simulant may not be described as having a diamond's properties (FTC, April 2, 2019).
Moissanite vs lab-grown diamond: how does the sparkle compare?
They do not look identical. GIA measured moissanite's dispersion, the spreading of white light into colors, at 0.104, and because moissanite is doubly refractive its facet edges can look doubled when you look closely. Some people love its colorful flashes; others prefer a diamond's look. The only reliable test is your own eye: see both side by side, in sunlight and indoors.
Can a jeweler tell moissanite from a diamond?
Yes, though not with every tool. GIA found that "the thermal probes currently on the market react to synthetic moissanite as if it were “diamond.”" A basic diamond tester alone is not enough. But moissanite "can be readily separated from diamond on the basis of its anisotropic optical character, which produces a doubling in the appearance of facet junctions," which a trained jeweler sees under magnification. Lab-grown diamonds are a separate question, answered with screening instruments; see how to tell if a diamond is lab-grown.
How popular is moissanite?
Among couples married in 2025, "moissanite and sapphires are the most popular non-diamond stones," while lab-grown center stones "now account for 61% of all engagement ring purchases" (The Knot Real Weddings Study 2026).
How do the prices compare?
We sell diamonds, natural and lab-grown, not moissanite, so we will not quote moissanite prices; compare real quotes for the same size and setting. What we can say: lab-grown diamonds cost far less than mined ones. The Knot's 2026 study puts the average lab-grown engagement ring at $4,300 against $7,000 for a natural stone, and our lab-grown diamond engagement rings are listed from $899.99 to $3,309.99 (as of October 21, 2026).
Which should you choose?
- Lab-grown diamond if you want a diamond: diamond hardness, diamond brilliance, and the word "diamond" on the paperwork with the lab-grown qualifier.
- Moissanite if you like its look and are comfortable choosing a simulant rather than a diamond.
For the bigger picture, read are lab-grown diamonds real diamonds? and our lab-grown vs natural comparison.
Compare lab-grown diamonds in Paramus
Our online catalog is lab-grown diamond jewelry, named lab-grown on every piece, and the showroom carries natural diamonds too. Browse lab-grown diamond rings or book an appointment to compare sizes and shapes in person.
Prestige Diamonds NJ
327 E State Route 4, Paramus, NJ 07652 (inside The Jewelry Center)
(201) 488-4280
