Gemnite | Round Moissanite

The stone guide

What is moissanite?

Moissanite is silicon carbide. The stones typically used in jewellery are lab-created. Moissanite and lab-grown diamond are distinct materials, each with its own appearance and properties.

Rainbow fire

Fire is the coloured light you see when a gem splits white light. Moissanite is known for strong rainbow flashes, especially under direct light.

Everyday wear

Moissanite rates about 9.25 on the Mohs hardness scale. That measures resistance to scratching. A well-fitted setting still matters, especially for a ring worn every day.

Why choose a round?

A round outline works in solitaires, stud earrings and pendants. If you’re matching a pair or fitting an existing setting, compare the diameter in millimetres.

Further reading from the Gemological Institute of America

Compare the stones

Hardness, sparkle and price

Moissanite sits close to diamond on the Mohs scale and resists scratches better than cubic zirconia. Its signature is rainbow fire. Brilliance is the white light a stone returns, while fire is the coloured flashes you see. Cut and lighting affect both.

Natural diamond

Mohs hardness: 10
Light and material: Earth-formed carbon crystal. A well-cut round has strong white brilliance and coloured fire.

US$3,910
1.01 ct, 6.36 × 6.40 mm, G/VS2, excellent cut. Diamond example

Lab-grown diamond

Mohs hardness: 10
Light and material: Lab-grown carbon crystal with the same basic optical and physical properties as natural diamond.

US$331
1.00 ct round, G/VS2, ideal cut. Diamond example

Moissanite

Mohs hardness: 9.25
Light and material: Lab-created silicon carbide. Strong white sparkle and more pronounced rainbow fire than diamond.

US$255
6.5 mm colourless round, 0.93 ct. Supplier catalogue, p. 25

Cubic zirconia

Mohs hardness: 8.5
Light and material: Lab-made zirconium dioxide crystal. It has less white brilliance and scratches more readily than moissanite.

US$8.40
6.5 mm white AA round. Supplier catalogue, p. 24

The Mohs scale ranks scratch resistance. The gaps between numbers represent unequal changes in hardness. GIA guide to diamond alternatives · GIA guide to lab-grown diamonds

These are US-dollar examples for loose stones from retailer listings and a supplier catalogue, checked in November 2026. Prices and availability can change. Gemnite prices will appear with each listing. The comparison uses similar visible size. Two stones of the same diameter can return light differently, so there is no single diamond price for matching a moissanite’s sparkle.

Where do other lookalikes fit?

Colourless sapphire (Mohs 9) is more scratch-resistant than CZ and has a quieter sparkle than moissanite. Glass imitations are softer and typically show less brilliance. GIA guide to gem imitations

Gemnite Black Friday collection

Loose round brilliant moissanite

The supplied sample report describes a 7.5 mm round brilliant moissanite and lists 1.5 carat, D colour, VVS1 clarity and excellent cut.

Gallery images illustrate the cut and appearance.

Sample grading report

Shown for reference. The report number and grades shown here relate to the supplied sample report.

Grading report · tap to enlarge

Report cover · tap to enlarge

Before you choose

Common questions

What is the difference between carats and millimetres?

Carats measure weight. Millimetres measure dimensions. For a round stone, the diameter tells you how wide it looks from above and helps a jeweller check whether it fits a setting.

What does diamond-equivalent weight mean?

It compares the apparent size to a diamond of a given weight. Moissanite and diamond have different densities, so compare the actual dimensions and ask which weight the listing quotes.

Can I use a loose stone in a custom piece?

Yes. Give your jeweller the stone’s diameter and depth so they can match it to a suitable setting.

How do I clean moissanite jewellery?

For most plain settings, use lukewarm water, mild dish soap and a soft brush. Ask your jeweller for care instructions if the piece has other stones, a special finish or a delicate setting.