What is moissanite?

Moissanite is a gemstone in its own right, not an imitation of something else. It looks like a diamond at a glance, and it is often worn where a diamond would be, but it is a different material with its own optical character. This guide covers what it is, where it comes from, how it looks and wears, and how it compares with diamond and the other stones people weigh it against.

What moissanite is made of

Moissanite is silicon carbide — one atom of silicon bonded to one atom of carbon, arranged in a tight, hard crystal. Diamond is pure carbon. The two share some traits (both are very hard and both carry heat well) but they are different minerals, which is why moissanite behaves differently in light.

In nature, moissanite turns up only as tiny grains, far too small to cut. There has never been a supply of natural moissanite gemstones, and there isn't one now.

Where it came from

The French chemist Henri Moissan found the first crystals in 1893, in fragments of the Canyon Diablo meteorite in Arizona. He took them for diamond at first, then identified them as silicon carbide, and the mineral was named moissanite in his honour. The full story, from the meteorite to the first gemstones, is in the history of moissanite.

Is moissanite lab-grown?

Yes — all gem moissanite is. A way to grow large single crystals of silicon carbide was only developed in the 1990s, and moissanite gemstones went on sale in 1998. Each crystal is grown, then cut and polished like any other gem. Because it is grown, it doesn't need to be mined, and the quality can be controlled: grown moissanite is typically very clean inside. Our science page explains more about the material.

Being lab-grown doesn't make it fake. A grown moissanite is real silicon carbide, just as a lab-grown diamond is real diamond. What it isn't is a diamond.

How it looks

Two numbers explain most of moissanite's appearance.

• Brilliance. Moissanite's refractive index is 2.65–2.69, against diamond's 2.42. It bends light more strongly, so a well-cut stone returns a great deal of bright, white sparkle.
• Fire. Its dispersion — how much it splits white light into colours — is 0.104, more than twice diamond's 0.044. That's the rainbow flash moissanite is known for, most noticeable in sunlight and in larger stones.

Moissanite is also doubly refractive, where diamond is singly refractive. Under a loupe, some stones show a slight doubling of the facet edges; a good cutter orients the stone to minimise it, and it can't be seen with the eye. Its fire depends on precise faceting, which is why cut quality matters so much.

Colour is graded on the familiar letter scale. D, E and F are colourless; G, H and I are near-colourless, with a faint warmth that shows most in larger stones and white metal. Moissanite is also made in colours such as black, blue and green. We sell only DEF colourless, VVS clarity stones — our grading guide explains the grades.

How it wears

At 9.25 on the Mohs scale, moissanite sits just below diamond (10) and above sapphire (9). It is also tough: it has no cleavage planes, so it is less prone to chipping than diamond. It suits an engagement ring or anything else worn every day.

It is stable, too. Moissanite doesn't cloud, fade or change colour over time. A moissanite that looks cloudy is simply dirty, and a clean brings it back.

Is moissanite a diamond?

No. It is silicon carbide, not carbon, and it looks different up close: more fire, and a stronger rainbow flash. It is sometimes called a “moissanite diamond”, but that is a misnomer. The confusion is understandable — even a thermal diamond tester can read moissanite as diamond, because both carry heat so well. A moissanite tester, which measures electrical conductivity, tells them apart.

We set out the full comparison, including what diamond does better, in moissanite vs diamond.

How it compares with other stones

Here is moissanite beside diamond, lab-grown diamond and two other stones often considered for rings.

Lab-grown diamond is optically identical to mined diamond; see lab-grown diamond or moissanite for how the two grown stones compare. Cubic zirconia is the stone most often passed off as moissanite. It is softer, so it is more easily scratched, and it bends light less, so it has less brilliance.

Why people choose moissanite

• The look. More fire than diamond, and top colour and clarity grades within reach.
• It lasts. Hard, tough and stable, so it keeps its looks through daily wear.
• The price. A diamond of the same size and colour costs many times more. Our price guide lists every size we sell.
• No mining. Every gem is grown, so its origin is known.

We have sold moissanite in South Africa since 1999. Every stone comes with a certificate of authenticity, a lifetime warranty, free tracked courier and 14-day returns, and each is shown at true size on a hand on its page. Browse the stones, or read our buyer's guide first.