White sapphire and moissanite are the two stones people most often choose instead of diamond for a ring meant to last. Both are tough and both are much cheaper than diamond. The choice comes down to how you want the stone to look.
What each stone is
White sapphire is colourless corundum, aluminium oxide, the same mineral as blue sapphire and ruby without the trace elements that colour them. It is mined or grown in a lab; most white sapphire in jewellery today is lab-grown.
Moissanite is silicon carbide, first found in a meteorite and now grown as single crystals. All gem moissanite is lab-grown. What is moissanite? covers it in full.
Side by side
| Moissanite | White sapphire | |
|---|---|---|
| Material | Silicon carbide | Aluminium oxide (corundum) |
| Hardness (Mohs) | 9.25 | 9 |
| Refractive index (brilliance) | 2.65–2.69 | 1.76–1.77 |
| Dispersion (fire) | 0.104 | 0.018 |
| Look | Bright, white sparkle with strong rainbow flashes | Soft, glassy, little colour |
| Between cleans | Stays bright | Dulls quickly, looks milky |
| On a thermal diamond tester | Usually reads as diamond | Fails |
How they look
This is the real difference. Moissanite's refractive index is among the highest of any gem, so a well-cut stone returns a great deal of light and looks lively from every angle. Its dispersion, more than twice diamond's, adds the rainbow fire it's known for. Our guide to why moissanite sparkles explains how.
White sapphire bends light far less. Much of the light that enters a white sapphire leaks out through the back rather than returning to your eye, so it looks quieter and more transparent: white and clean, but without much sparkle or fire. Some people prefer that calm, understated look. Beside a moissanite or a diamond, though, it can look like glass.
Why white sapphire looks dull between cleans
A stone with a low refractive index is more easily dulled by a film of skin oil or soap, because there's less internal reflection to overcome it. A white sapphire worn every day can look grey or milky within days of a clean. Moissanite gets dirty too, but it keeps more of its brightness through the film. Our cleaning guide covers how to keep either stone bright.
Durability
Both stones will last a lifetime of daily wear. White sapphire, at 9 on the Mohs scale, is very hard, and moissanite at 9.25 is a little harder. Neither will be scratched by ordinary dust. Moissanite also has no cleavage planes, so it is a little more resistant to chipping, though any stone can chip at an edge or point under a hard knock.
Colour
Lab-grown white sapphire is usually colourless. Mined white sapphire often carries a faint grey, yellow or blue tint. Moissanite is graded on the diamond colour scale; ours is all DEF, colourless. The colour chart shows the grades.
Price
Lab-grown white sapphire and moissanite are broadly similar in price at the same size, and both cost a fraction of diamond. Mined white sapphire costs more than lab-grown and varies with quality. The moissanite price guide lists every size we sell.
Which should you choose?
Choose white sapphire if you want a quiet, glassy stone, or if a mined, natural gem matters to you. Choose moissanite if you want a stone that sparkles: brighter than white sapphire, fierier than diamond, and close to diamond in hardness.
If you're weighing moissanite against the other options too, see moissanite vs diamond, lab-grown diamond or moissanite and moissanite vs cubic zirconia, or browse the stones.
Is moissanite or white sapphire better?+
For sparkle, moissanite: it is far more brilliant and has more than five times white sapphire's fire. Both are hard enough for everyday wear. White sapphire suits someone who wants a quieter, glassier stone.
Is white sapphire harder than moissanite?+
No. White sapphire is 9 on the Mohs scale and moissanite is 9.25. Both are very hard, and only diamond is harder than either.
Does white sapphire look like a diamond?+
It looks white and clean, but it has far less brilliance and fire than diamond, so beside one it looks glassier. It also dulls quickly between cleans.
Does white sapphire get cloudy?+
It doesn't change, but its low refractive index means a film of oil or soap dulls it quickly, so it can look milky between cleans. Regular cleaning brings it back.