What each stone is made of
Moissanite is silicon carbide, written SiC. Every stone sold as moissanite today is grown in a laboratory by a thermal process, then cut and polished like any other gem. It is a material in its own right, not a diamond imitation made of glass or cubic zirconia.
Lab-grown diamond is carbon with the same crystal lattice as a mined diamond. Two methods produce it: CVD, which grows the crystal layer by layer in a vacuum chamber, and HPHT, which reproduces the heat and pressure of the earth's mantle. A jeweler cannot separate a lab-grown stone from a mined one with a loupe. The difference shows up under instruments that read growth patterns, which is why grading labs examine every stone before issuing a report.
Hardness and how each stone ages
Diamond sits at Mohs 10, the top of the scale. Moissanite sits at 9.25. Both are hard enough for a ring worn every day, and neither will scratch from ordinary contact with clothing, keys, or a countertop.
Hardness measures scratch resistance, not toughness. A hard stone can still chip if it takes a square hit on a thin edge, and a high setting exposes more of the stone than a bezel does. Moissanite has one practical advantage in repair work: it is thermally stable, so a jeweler can apply a torch to the mounting during sizing or re-tipping without damaging the stone.
Sparkle comes from dispersion
Dispersion is the property that splits white light into color. Moissanite measures 0.104 and diamond measures 0.044, so moissanite returns more than twice the fire. Under strong light, especially in stones above one carat, that reads as visible rainbow flashes across the facets.
Refractive index follows the same pattern. Moissanite runs 2.65 to 2.69 against diamond's 2.417. A higher number means the stone bends light more sharply, which adds brightness and changes how the facet pattern looks in photographs. Some people want that contrast. Others prefer the quieter return of a diamond.
Color, clarity, and the scales used
Diamonds are graded for color on a scale from D, colorless, to Z, with a visible tint. Clarity runs from FL, flawless, to I3, where inclusions are visible to the unaided eye. Lab-grown diamonds use the same scales because they are diamonds, and the same labs grade them.
Moissanite is not graded on those scales. Suppliers describe it with their own color bands, usually near-colorless to colorless, and clarity is judged by eye. A well-cut moissanite at a good color grade looks clean without magnification, which is the standard most buyers actually apply.
| Property | Moissanite | Lab-grown diamond |
|---|---|---|
| Composition | Silicon carbide (SiC) | Carbon |
| Mohs hardness | 9.25 | 10 |
| Refractive index | 2.65 to 2.69 | 2.417 |
| Dispersion | 0.104 | 0.044 |
| Specific gravity | 3.20 to 3.24 | 3.52 |
| Color grading | Supplier color bands | D to Z |
| Clarity grading | Judged by eye | FL to I3 |
| Certificate | GRA, inscription matched | GRA or full lab report |
Cost and what the difference buys
Lab-grown diamonds cost far less than mined diamonds of equivalent grade, and moissanite costs less again at the same face-up size. The gap widens as carat weight climbs. At one carat the difference is noticeable. At three carats it changes what a given budget can build.
We quote both stones against the same setting so the comparison stays honest. A three-carat moissanite in a well-made mounting is a real option. So is a smaller lab-grown diamond with a better cut, and cut is the grade most people notice first.
Resale is the part buyers forget. A lab-grown diamond trades at a fraction of its retail price on the secondary market, and moissanite trades lower still. Treat either purchase as a piece you will keep rather than an asset, and the price comparison becomes simpler.
Certification and inscription
GRA certificates are available with the moissanite and lab-grown diamonds we supply. Each certificate carries a number, and the stone is laser inscribed to match. On lab-grown diamonds, reports from the major grading labs can also be arranged.
Ask for the certificate number and check it against the inscription with a loupe. That one step confirms the paper and the stone belong together, which matters on an insurance schedule and matters again if the piece is ever sold.
Which stone fits which ring
- Moissanite suits large center stones, halo designs, and any build where budget should go into metal and setting work.
- Lab-grown diamond suits buyers who want diamond named on the certificate and will trade size for that.
- Either stone works in 10K, 14K, or 18K gold, PT950 platinum, and sterling silver.
Stone choice rarely decides whether a ring looks good. Proportion, setting height, and band width do more. If the design is still open, start with the custom design service and approve the CAD render before any stone is ordered. Current options sit on the loose stones page, and our learn section covers grading in more depth.