Moissanite 101
Hardness Is Not Toughness: Can Moissanite Chip?
Two different properties, routinely confused β and only one of them is what actually breaks stones.
Written by the Mapple Gems workshop, Surat Β· Updated 11 September 2026
Short answer
Yes, moissanite can chip β and so can diamond. Hardness resists scratching; toughness resists breaking under impact, and they are separate properties. Moissanite is Mohs 9.25, so it will not abrade in ordinary life, and it is genuinely tough β but no faceted gem is unbreakable. The realistic risk is a sharp knock against stone, tile or metal, concentrated on exposed points and thin girdles. That makes chipping a setting question far more than a material one.
βIt is a 9.25, so it is basically indestructibleβ is the most common misunderstanding in this material β and the reason some people are surprised by a chip that was, in fairness, always possible.
The two properties, separated
| Property | Resists | Everyday consequence |
|---|---|---|
| Hardness (Mohs) | Scratching and abrasion | Whether it dulls over years |
| Toughness | Cracking and chipping on impact | Whether a knock damages it |
They do not track each other. Diamond is the hardest natural material at Mohs 10 and can still cleave along its crystal planes if struck at the wrong angle β which is precisely how diamond cutters shape it. Jade is far softer and remarkably difficult to break. Hardness and toughness are simply different questions.
Moissanite scores well on both: Mohs 9.25 puts it well clear of the quartz in household dust at 7, so abrasion is not a practical concern, and its toughness is good. But βgoodβ is not βinfiniteβ, and no faceted stone is.
Chips happen at points and thin girdles, which is a design decision rather than a material one. A faceted stone is not uniformly strong. The points of pears, marquises and hearts are the thinnest, most exposed geometry in jewellery, and the girdle β the outer edge β is where the metal grips and where a knock lands first. Cut extremely thin, a girdle is genuinely fragile. So the same stone in two different settings has very different risk: a pear with a proper V-prong over its point is well protected, while one with a round prong beside the point is exposed. Ask about girdle thickness on the report, and insist on a V-prong over every point and a prong over every cut corner. That is where chip risk is actually controlled.
What realistically causes a chip
- A hard knock against stone, tile or metal. Door frames, kitchen worktops, car doors, gym equipment. Sharp, sudden, at an unlucky angle.
- During setting. Uncommon but not rare β setting applies force to a finished stone, and points and thin girdles are where it goes wrong.
- During a later repair. Resizing and re-tipping involve heat and pressure near the stone. Tell any jeweller what the stone is before they work on it.
- An ultrasonic cleaner on an already-damaged stone. Vibration can extend an existing fracture.
Notice that three of the four happen at a bench rather than in daily life. Ordinary wear is not the main risk.
Reducing the risk
- Bezel or half-bezel for anyone with hands-on work β a continuous collar protects the girdle completely.
- V-prongs on every point, and a prong over each corner of an emerald or Asscher.
- Avoid an extremely thin girdle. It is stated on a grading report; aim for the middle of the range.
- Lower profile. A stone that sits high meets more things, and with more leverage.
- Take it off for the gym. Grip loads and metal equipment are the highest-risk combination in ordinary life.
If it does chip
Three options, in order of preference.
Reposition it. A small chip at the girdle can sometimes be hidden under a prong or a bezel by rotating the stone in its setting. Cheapest by a distance, and worth asking about first.
Replace the stone. With moissanite this is straightforward and inexpensive β the material is consistent and comes in standard millimetre sizes, so a replacement drops into the existing setting. This is a genuine advantage over a mined stone, where matching is a sourcing exercise.
Recut it. Possible, but it produces a smaller stone that no longer fits the setting, so it usually means a new head as well. Rarely the sensible route unless the stone is large.
The honest comparison with diamond
Being straight about this, since it is the reason people ask.
Both materials can chip, both are chipped in the same circumstances, and both are protected by the same setting decisions. Diamond has cleavage planes and moissanite does not, which is a point in moissaniteβs favour; diamond is harder, which matters for abrasion rather than impact.
For practical purposes the difference is small enough that it should not drive the decision. What should drive it is the setting: a well-built bezel in either material outlasts a badly-built prong setting in either material.
Frequently asked questions
Can moissanite chip or break?
Yes, as can diamond. Hardness resists scratching while toughness resists impact, and they are separate properties β moissanite is Mohs 9.25 so abrasion is not a practical concern, and its toughness is good, but no faceted gem is unbreakable. The realistic risk is a sharp knock against stone, tile or metal.
Where do stones chip?
At points and thin girdles. The points of pears, marquises and hearts are the thinnest exposed geometry in jewellery, and the girdle is where a knock lands first. That makes chip risk a setting question β a V-prong over every point, a prong over every cut corner, and a girdle that is not extremely thin.
Can a chipped stone be fixed?
Often a small chip at the girdle can be hidden by rotating the stone so a prong or bezel covers it β cheapest and worth asking about first. Otherwise replacement is straightforward with moissanite, since the material is consistent and comes in standard millimetre sizes, so a new stone drops into the existing setting.
Is moissanite more likely to chip than diamond?
Not meaningfully. Both chip in the same circumstances and are protected by the same setting decisions. Diamond has cleavage planes that moissanite lacks, which favours moissanite; diamond is harder, which matters for abrasion rather than impact. A well-built bezel in either material outlasts a poorly-built prong setting in either.
Ask about the girdle and the prongs.
Chip risk is controlled at the setting stage, and it is a conversation worth having before casting.
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