Moissanite rates 9.25 on the Mohs hardness scale. Diamond rates 10. Sapphire rates 9. For a ring you'll wear every day for decades, that number matters more than almost anything else on the certificate, so here's exactly what it means in practice.
Hardness: what 9.25 actually buys you
The Mohs scale measures resistance to scratching. Diamond, at 10, is the hardest substance on earth. Moissanite, at 9.25, is the second hardest gemstone used in fine jewellery, ahead of sapphire and ruby at 9 and emerald at roughly 7.5.
What matters day to day is what your ring actually touches. Household dust carries quartz and mineral particles rated around 7 on the Mohs scale, nowhere near hard enough to mark a 9.25 stone. Gold, platinum, and silver are all softer than moissanite too, so contact with other jewellery or cutlery won't scratch it either. The one thing that can scratch moissanite is diamond, so it's worth not storing a moissanite ring loose against a diamond one, but everything else in normal daily life is softer than the stone itself.
Hardness and toughness are different things
Hardness measures scratch resistance. Toughness measures resistance to fracturing on impact, and they don't always move together. Diamond is the hardest material there is, yet it splits along four cleavage planes with a single well-placed blow, because its atomic structure has built-in weak points.
Moissanite has no cleavage planes. There's no structural line along which the stone wants to split, so a knock against a hard surface is unlikely to chip or crack it under normal conditions. That's a genuine practical advantage over diamond for anyone who works with their hands, trains regularly, or just wants one less thing to worry about.
What daily wear actually does to the stone
An engagement ring worn every day meets soap, water, cleaning products, gym equipment, keyboards, and steering wheels, the full range of ordinary contact. Most gemstones at lower hardness ratings pick up visible surface wear over years of that. Moissanite, at 9.25, doesn't. The stone itself won't degrade, and its optical performance stays consistent because the surface polish stays intact.
The setting is a separate story. Prongs and metal do wear over years, which is why we recommend having the setting checked periodically, the same as we would for any ring. That's maintenance on the metal, not the stone. Read our warranty and guarantee page for exactly what's covered if anything in the setting does need attention.
How this compares across our own range
If you're choosing between moissanite and one of our lab-grown diamond rings, hardness alone shouldn't decide it. A lab diamond is chemically identical to a mined diamond and rates a full 10 on the Mohs scale, but it does have diamond's cleavage planes. Moissanite gives up a small amount of raw hardness for a genuine toughness advantage. Both are excellent choices for a ring worn every day; which one suits you comes down to budget, brilliance preference, and how you feel about that trade-off, not durability alone.
Moissanite vs diamond on durability
Diamond edges out moissanite on raw hardness, 10 versus 9.25, but in daily wear that gap is irrelevant. The only thing that scratches moissanite is diamond, and the only thing that scratches diamond is diamond, so both stones are harder than anything else they'll meet in normal life. Where moissanite actually pulls ahead is toughness: no cleavage planes means no structural weak point, which diamond has despite its higher hardness number. Our full moissanite vs diamond comparison covers the rest of the differences that matter to a buyer.
Frequently asked questions
Will moissanite scratch in daily wear?
No. Nothing you'll encounter in normal daily life is hard enough to scratch a 9.25 Mohs stone, aside from another diamond.
Is moissanite as durable as diamond?
For practical purposes, yes. It's slightly softer on paper, but it has no cleavage planes, which makes it more resistant to chipping on impact than diamond.
Can moissanite chip or break?
Under normal wear, it's extremely unlikely. Moissanite has high toughness and no cleavage planes, so it handles everyday knocks well.
Does moissanite lose its sparkle over time?
No. Because the surface stays intact, a well-maintained moissanite ring keeps its original brilliance for decades. Routine cleaning is all it needs.
Every moissanite we set is GRA certified and made to order in our South African workshop. Browse the full moissanite engagement ring collection, read how it compares on brilliance and value against diamond, or start a free design consultation to talk through stone and setting together.