Does Moissanite Cloud Over Time?

No. Moissanite does not cloud, yellow or lose its fire with age — it is a hard, non-porous crystal with nothing in it to degrade. A moissanite that looks dull has a film on its surface: skin oil, soap residue, hand lotion, hairspray. It cleans off in a few minutes and the stone looks new again.

This question gets asked more than any other about moissanite, usually in some version of “will it still look like this in five years?” The short answer is yes, and the reason is worth understanding, because it also tells you what a dull-looking stone actually needs.

Why clouding isn't possible

Clouding, in the sense people usually mean, requires one of two things: a porous material that absorbs what it touches, or a soft material whose polish wears away. Moissanite is neither. Silicon carbide is a dense crystal with no pore structure, so nothing soaks into it. And at 9.25 on the Mohs scale it sits just under diamond, which means very few things you encounter in a day are hard enough to scratch its surface.

It is also chemically stable. Moissanite doesn't oxidise, doesn't react with skin, and doesn't yellow with UV exposure. There is no internal process by which a moissanite gets worse.

What actually makes a stone look dull

A film. Skin oil is the main culprit, and it builds up faster than people expect on a ring worn daily. Hand lotion, sunscreen, soap that isn't fully rinsed, hairspray drift, and the residue left by dish detergent all add to it.

The effect is specific: the stone stops throwing light. Brilliance depends on light entering a facet, bouncing inside the stone and leaving through the top. A greasy film scatters light at the surface before it ever gets in. The stone doesn't look damaged, it looks flat — and because the change is gradual, most people read it as the stone going dull rather than as dirt.

The tell is that it is worse underneath. Turn a ring over and look at the back of the setting: that is where oil collects, and it is where cleaning makes the most visible difference.

How to bring it back

Warm water, a drop of plain washing-up liquid, and a soft toothbrush. Soak for ten minutes, brush gently around and behind the stone, rinse thoroughly, dry with a lint-free cloth. That is the whole procedure, and for a daily-worn piece it is worth doing every few weeks.

Avoid anything abrasive — toothpaste, baking soda, scouring cream — and avoid bleach and chlorine, which won't touch the stone but will attack the metal holding it. If your piece is plated, be gentler still: the plating is the part that wears, not the stone.

What can actually go wrong

Two things, and neither is the stone clouding. The first is surface scratching on the metal, which is normal and shows up long before anything happens to the stone. The second is a loosening setting — prongs move over years of knocks, and a stone that sits slightly low or catches on fabric should be checked.

If a moissanite genuinely looks different after cleaning, it is nearly always the setting or the plating that has changed, not the stone.