Moissanite and diamond look alike, but they are different gemstones. Diamond is pure carbon and the hardest natural mineral (10 on the Mohs scale). Moissanite is silicon carbide made in a laboratory, almost as hard (9.25), with more rainbow fire and a much lower price. Both are durable enough for everyday rings; the right choice depends on budget and the kind of sparkle you prefer.
Side by side
Moissanite vs diamond at a glance
| What it is | Moissanite: silicon carbide · Diamond: pure carbon |
|---|---|
| Origin | Moissanite: made in a laboratory (natural is extremely rare) · Diamond: mined or lab-grown |
| Hardness | Moissanite: 9.25 · Diamond: 10 |
| Refractive index | Moissanite: about 2.65–2.69 · Diamond: 2.42 |
| Fire (dispersion) | Moissanite: 0.104 · Diamond: 0.044 |
| Weight | Moissanite is about 10% lighter for the same size |
| How it's chosen | Moissanite: by millimetres · Diamond: by carats |
| Price | Moissanite costs a small fraction of a similar-looking diamond |
The basics
What is the difference between moissanite and diamond?
Diamond is carbon crystallised under enormous pressure. Moissanite is silicon carbide; it was first found in a meteor crater in 1893, and because natural moissanite is so rare, almost all moissanite sold today is made in a laboratory. It is a gemstone in its own right, not glass and not a diamond imitation like cubic zirconia.
"Across a room, they look alike. Up close in sunlight, moissanite throws more rainbows."
Compare
How do they compare in practice?
💪 Hardness
Diamond 10, moissanite 9.25. Both are hard enough for everyday rings.
🌈 Sparkle
Moissanite bends light more and splits it into more colour, so it shows more rainbow fire, especially in larger stones.
⚪ Colour
Colourless moissanite faces up very white; in some lights large stones can show a faint tint.
⚖️ Weight
Moissanite is lighter, so it is chosen by millimetres rather than carats.
💰 Price
Moissanite lets you choose a bigger stone for the same budget.
🌱 Origin
Moissanite gems are made in a laboratory, with no mining of the stone itself.
Sizing
What size moissanite looks like a diamond?
Because moissanite is lighter, compare by millimetres. A 6.5 mm round moissanite weighs about 0.88 carats but looks like a one-carat diamond. In India, stones are also weighed in ratti; on our site, ratti is carats divided by 0.91.
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Pick the shape
Round, oval, cushion, pear, emerald cut and more.
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Choose the size in mm
Each size also shows carats and ratti.
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See it at actual size
On our moissanite pages, match your screen to a bank card or a ₹10 coin to see every size at true scale.
Myths, cleared up
Myth: "Moissanite is fake diamond."
It is a different gemstone. It is only dishonest if sold as diamond; we always label moissanite as moissanite.
Myth: "Moissanite turns cloudy over time."
It does not change; cloudiness is dirt and cleans off.
Myth: "Moissanite is the same as cubic zirconia."
CZ is much softer (about 8) and scratches; moissanite is 9.25.
Myth: "No one can tell them apart."
A jeweller with a moissanite tester can. Basic thermal testers may read moissanite as diamond.
Moissanite vs diamond: questions people ask
Is moissanite as good as diamond?
For looks and everyday wear, moissanite performs very well: it is nearly as hard, more fiery and far less expensive. Diamond is harder and has a whiter sparkle. Which is better depends on what you value.
Can a jeweller tell moissanite from diamond?
Yes, with a moissanite tester or under magnification. Basic thermal diamond testers often read moissanite as diamond.
Does moissanite change colour over time?
No. Moissanite keeps its colour and sparkle; just clean it regularly.
What size moissanite equals a 1 carat diamond?
A round moissanite of about 6.5 mm looks like a one-carat diamond, though it weighs about 0.88 carats.
Is moissanite real or synthetic?
Moissanite is a real mineral. The gems sold today are made in a laboratory because natural moissanite is extremely rare.
Is moissanite good for an engagement ring?
Yes. Its hardness makes it suitable for daily wear, and many couples choose it for value and sparkle.
Carat and ratti figures are approximate averages.
See moissanite by shape and size
Every shape has a size chart in millimetres, carats and ratti, with a true-to-size view on your own screen.
Shop moissanite
