The moissanite vs diamond question usually gets answered with adjectives. It deserves numbers. Moissanite is lab-created silicon carbide — a real gemstone in its own right, but not a diamond — and on the measurable properties the two stones simply trade blows: moissanite bends and splits light more aggressively, diamond is harder, and the price gap is enormous. Here is every figure that matters, stated plainly.
| Property | Moissanite | Diamond |
|---|---|---|
| Composition | Silicon carbide (lab-created) | Crystallised carbon |
| Refractive index | 2.65–2.69 | 2.42 |
| Dispersion (fire) | 0.104 | 0.044 |
| Mohs hardness | 9.25 | 10 |
| Light behaviour | Doubly refractive | Singly refractive |
| Typical grades (lab-created) | D–F colour, VVS1 clarity (as stated by growers/sellers, not independently graded) | Graded stone by stone |
| Relative price | A fraction of a comparable diamond | The benchmark |
What is moissanite, exactly?
Moissanite is silicon carbide. Natural moissanite is so rare it was first identified in fragments of a meteorite, so essentially every stone in jewellery today is lab-created. That makes it a genuine gemstone with its own chemistry and its own optics — not an imitation diamond, and not a diamond by another name. A diamond is crystallised carbon; moissanite is a different material that happens to be one of the very few gems hard and brilliant enough to sit beside it.
Which has more brilliance and fire?
Moissanite, by a wide margin — and measurably so. Its refractive index of 2.65–2.69 exceeds diamond's 2.42, so it bends light more sharply and returns more of it to the eye. Its dispersion — the property that splits white light into rainbow flashes — is 0.104, more than double diamond's 0.044.
Whether that is an upgrade is a matter of taste. In larger stones, moissanite's fire can read as a deliberate rainbow shimmer; some people love the effect, others prefer a diamond's whiter, more restrained sparkle. Moissanite is also doubly refractive where diamond is singly refractive, which adds to the liveliness. If you want a quieter stone, smaller sizes and step cuts such as the emerald cut tame the fire considerably.
Which is harder — and does moissanite last?
Diamond wins on hardness: 10 on the Mohs scale against moissanite's 9.25. Be honest with the scale, though — Mohs is not linear, and the gap between 9.25 and 10 is larger than it looks on paper. Diamond is meaningfully harder in absolute terms.
In practice, both are everyday stones. At 9.25, moissanite is harder than sapphire or ruby and than any dust or grit it will ordinarily meet, so it resists scratching through daily wear. It is also a stable crystal: it does not fade, yellow, or lose its fire over time. When a moissanite looks cloudy, the cause is almost always surface residue — skin oils, soap film, lotion — and warm water with mild dish soap restores it.
Does moissanite pass a diamond tester?
Usually, yes. Most pen-style testers measure thermal conductivity, and silicon carbide conducts heat much as diamond does, so moissanite commonly reads as "diamond" on those devices. Testers that also check electrical conductivity will flag it, because moissanite conducts electricity in a way diamond generally does not. This is precisely why moissanite should always be sold as moissanite, clearly and in writing — the tester result is a quirk of physics, not a licence to blur the two stones.
How do colour and clarity compare?
Because moissanite is grown under controlled conditions, growers and sellers typically describe quality lab-created stones as D–F colourless with VVS1 clarity - their grading, not an independent lab's, and not a grade we apply to our own stones — grades that, in a diamond, command steep premiums and are priced per step. With a diamond you choose, and pay for, your position on the colour and clarity scales; with moissanite the near-top grades are the norm.
One honest caveat: those moissanite grades come from the grower or seller, not from the GIA, which does not issue grading reports for moissanite. Certificates from labs such as "GRA" do not carry the weight of a GIA report, so judge a moissanite by the stone and the seller's transparency rather than by the paperwork.
What about price — and resale?
Price is the widest gap of all. A moissanite of a given size costs a small fraction of a comparable natural diamond, which is what makes a well-cut, colourless, eye-clean stone attainable in 925 sterling silver at prices that would not buy a diamond of any real presence.
The honest counterpart: moissanite has essentially no resale market. Neither, for what it is worth, do most diamonds recover what was paid for them — but a diamond retains some liquidity and moissanite does not. Buy moissanite to wear it, not as a store of value.
So which should you choose?
- Choose a diamond if tradition, maximum hardness, or the name itself matters to you — those are legitimate reasons, and no number changes them.
- Choose moissanite if you want more fire, more size, and near-flawless grades for a fraction of the outlay — and you are content that it is moissanite.
Neither choice is wrong; only pretending one stone is the other is. Maison Noctaura works on the second premise: lab-created moissanite described as near-colourless and eye-clean, uncertified, set in solid 925 sterling silver - the same words the product pages use, because they are the words we can stand behind. If the numbers speak to you, the collection is where they take shape.
The same numbers, on real pieces
The figures above are the ones printed on our own product pages. The Eclipse Eternity Band states 0.06 ct across its line of stones on a 5.4 mm band. The Coronation Pendant states an 11 mm round stone at 5 ct. The Aureole Halo Ring states a 6 × 3.6 mm centre at 0.5 ct in a double-halo setting. Sizes and weights are printed, not implied.
