DESIGN YOUR OWN ENGAGEMENT RING
We sell both, so we have no reason to talk you into either. What follows is what actually separates them.
The short version: a lab grown diamond is a diamond. Moissanite is a different gemstone that happens to be colourless and extremely brilliant. Neither is a fake version of the other, and the right choice depends on what you want the ring to do.
Side by side
| Lab Grown Diamond | Moissanite | |
|---|---|---|
| Material | Pure carbon | Silicon carbide (SiC) |
| Hardness (Mohs) | 10 | 9.25 |
| Refractive index | 2.42 | 2.65 – 2.69 |
| Dispersion (fire) | 0.044 | 0.104 |
| Light behaviour | Singly refractive | Doubly refractive |
| Certification | IGI / GIA, graded on the 4Cs | Usually a supplier report, not 4C graded |
| Relative price | Higher | Lower |
What those numbers mean in daylight
Sparkle looks different, not weaker
This is the difference most people actually notice, and the table above explains it.
Dispersion is a stone's ability to split white light into spectral colours. Moissanite's dispersion is roughly 2.4 times that of diamond. In practice, moissanite throws noticeably more coloured flashes — reds, greens, blues — especially in direct sun or under spotlights. People describe it as "fiery" or "disco ball".
Diamond returns more white light and less colour. The effect is brighter and cleaner, with flashes that read as white sparkle rather than rainbow.
Neither is objectively better. Some people love moissanite's fire. Others find it reads as obviously not-a-diamond, and prefer diamond's restraint. Look at both under a shop light and under daylight before deciding — the gap is much more visible in some lighting than others.
Size matters here too. Under about 1 carat the difference is subtle. Above 2 carats, moissanite's fire becomes quite pronounced.
Double refraction
Moissanite is doubly refractive: light entering the stone splits into two rays. Look down through the table of a larger moissanite at an angle and you can sometimes see facet edges appearing doubled, a slightly blurred effect. Diamond is singly refractive and never does this.
It is easiest to see in bigger stones and in step cuts like emerald and asscher, where the long open facets show it clearly. In a brilliant cut under 1.5 carats, most people never notice.
Hardness
Diamond is 10 on the Mohs scale. Moissanite is 9.25. Both are exceptionally hard and entirely suitable for daily wear — for context, sapphire is 9 and has been used in rings for centuries.
The Mohs scale is not linear, though. The gap between 9.25 and 10 is larger than the numbers suggest, and diamond remains the hardest known natural material. Over decades of daily wear, a diamond will hold its polish marginally better. This is a real difference, but a small one, and it is not a reason to rule out moissanite.
Neither stone is immune to chipping. Hardness resists scratching; it does not mean unbreakable. Any stone with a sharp point — pear, marquise, princess — benefits from a setting that protects the tip.
Colour
Lab grown diamonds are graded D to Z. We generally stock D–G, which reads colourless to the eye.
Modern moissanite is typically sold as colourless or near-colourless, and quality has improved considerably. Older material had a noticeable yellow or green cast, particularly in larger sizes; current production is much cleaner. In very large stones a faint warmth can still show under certain lights.
Price
Moissanite costs substantially less than a lab grown diamond of the same size, which in turn costs substantially less than a mined diamond.
The practical consequence is size. A budget that buys a modest lab grown diamond will buy a considerably larger moissanite. If carat size is your priority, moissanite gets you there for less.
Which should you choose?
Choose a lab grown diamond if you want a diamond specifically — the material, the certificate, the grading, the tradition of it. If it would bother you that the stone is not a diamond, that feeling will not fade, and no amount of technical argument will change it. Buy the diamond.
Choose moissanite if you love the extra fire, you want maximum visual size for the budget, or the distinction between materials genuinely does not matter to you. It is a beautiful stone in its own right, not a compromise.
Consider moissanite for a second piece — a travel ring, an anniversary band, a right-hand ring — even if your main stone is a diamond. Many of our customers own both.
A note on honesty
Some sellers describe moissanite in language designed to blur the line — "diamond simulant" used vaguely, or comparisons that quietly omit that it is a different material. We would rather be direct: moissanite is silicon carbide, it is not a diamond, and it is genuinely lovely.
Whichever you choose, you should know exactly what is on your hand.
