Moissanite vs Diamond: The Honest Comparison (2026 Guide)
The quick answer
Moissanite is a gemstone in its own right — not a fake diamond. It's nearly as hard as diamond, sparkles with even more fire, and costs a fraction of the price. A lab grown diamond, on the other hand, is a real diamond: chemically and optically identical to a mined one, just made above ground and priced well below it.
We sell both moissanite and lab grown diamonds, so we have no reason to talk one up over the other. Here is the honest comparison, point by point.
What is moissanite?
Moissanite is silicon carbide, a crystal first discovered by Nobel Prize-winning chemist Henri Moissan in a meteor crater in 1893. Natural moissanite is so rare that virtually every stone sold today is lab created — grown to be optically flawless, eye-clean and colourless.
It is not cubic zirconia. CZ is soft, clouds over time and dulls within years. Moissanite is the second-hardest gemstone used in jewellery, after diamond itself, and keeps its sparkle for life.
Moissanite vs diamond at a glance
| Moissanite | Diamond (lab or mined) | |
|---|---|---|
| Hardness (Mohs) | 9.25 | 10 |
| Brilliance (refractive index) | 2.65–2.69 (higher) | 2.42 |
| Fire (dispersion) | 0.104 (rainbow flashes) | 0.044 (white sparkle) |
| Colour | D colour, VVS clarity | Graded D–Z, per IGI certificate |
| Everyday durability | Excellent — scratch resistant for life | Excellent — hardest known material |
| Price | $ | $$ lab grown / $$$$ mined |
| Passes a thermal diamond tester? | Often yes | Yes |
Hardness and durability
Diamond is the hardest known gemstone at 10 on the Mohs scale. Moissanite sits at 9.25, second overall and comfortably harder than sapphire (9), ruby (9) and emerald (7.5–8). For context, everyday household dust contains quartz at hardness 7 — that's what slowly scratches softer stones, and both diamond and moissanite shrug it off.
In practical terms, both resist everyday scratching for a lifetime. Neither is unbreakable, though: a sharp knock at the wrong angle can chip any stone, which is why our Ring Care Guide matters whichever you choose.
Sparkle: they shine differently
Diamond gives balanced white light return — the classic icy look. Moissanite has a higher refractive index (2.65 vs 2.42) and more than double the fire (dispersion 0.104 vs 0.044), producing vivid rainbow flashes, especially in sunlight.
Some people love that extra liveliness; others prefer diamond's restraint. Neither is better — they are simply different personalities. Larger moissanite stones show the rainbow effect more strongly, which is one of the few ways a trained eye can tell them apart.
Colour and clarity
Aura Moissanite is selected for D-colour whiteness and VVS-grade clarity across the board. With diamonds, colour and clarity vary stone by stone and are documented on the IGI certificate that accompanies every certified diamond we sell, so you know exactly what you are getting.
Price: the biggest practical difference
A moissanite typically costs a small fraction of an equivalent lab grown diamond, which itself costs far less than a mined diamond of the same size and quality — mined stones often reach five figures for what a lab diamond delivers for thousands less. That difference can mean a larger stone, a solid gold setting, or a honeymoon.
Does moissanite pass a diamond tester?
Usually, yes. Standard handheld testers measure thermal conductivity, and moissanite conducts heat similarly to diamond, so most thermal testers read it as "diamond." Only dual electrical/thermal testers or professional gemmological inspection reliably separate the two. Lab grown diamonds always test as diamond — because they are diamond.
Ethics
Both our moissanite and our lab grown diamonds are created above ground, guaranteed conflict-free and ethically sourced. No mining, no supply-chain ambiguity, dramatically less environmental impact. No compromise either way.
The bottom line
Choose a lab grown diamond if certification and the classic diamond identity matter most to you — you want the crisp white sparkle and the words "it's a real diamond" to be true without asterisks.
Choose moissanite if you want maximum fire and maximum value — the biggest, brightest stone your budget allows, with the savings going toward the wedding or the house deposit.
Many of our designer solitaires are available in both stones in 10K, 14K or 18K solid gold, so you can compare the exact same ring either way. And if you are still torn, message our team via chat; helping you choose is genuinely our favourite part of the job.
Frequently asked questions
Is moissanite a fake diamond?
No. Moissanite is its own gemstone (silicon carbide) with its own properties. It isn't trying to be a diamond — it out-sparkles one.
Will moissanite get cloudy over time?
No. Unlike cubic zirconia, moissanite is hard and chemically stable. With basic cleaning it sparkles the same in 30 years as it does today.
Are lab grown diamonds real diamonds?
Yes. Lab grown diamonds are chemically, physically and optically identical to mined diamonds — carbon crystallised in the same structure. The only difference is origin and price.
Can people tell moissanite from diamond?
At a glance, almost never. In large stones, a trained eye may notice moissanite's stronger rainbow fire. A standard thermal diamond tester usually can't tell them apart either.
Does moissanite hold its value?
Neither moissanite nor diamonds should be viewed as financial investments — even mined diamonds typically resell far below retail. Buy the stone you love at the price that makes sense for your life.