What is moissanite, exactly?

Moissanite is a naturally occurring mineral first discovered in 1893 by French chemist Henri Moissan, who found tiny silicon carbide crystals inside a meteorite crater in Arizona. Natural moissanite is so rare that virtually every moissanite gemstone sold today, including anything you'll find in a UK jewellery shop, is grown in a laboratory using advanced crystal-growing technology.

Chemically, moissanite is silicon carbide (SiC). A diamond is pure carbon. They're not the same material, they don't form the same way, and under a jeweller's loupe they behave differently, which is exactly why moissanite has its own name and its own place in fine jewellery, rather than being sold as a diamond substitute.

What is a diamond, exactly?

A diamond is a crystal made entirely of carbon atoms, formed under extreme heat and pressure over one to three billion years, usually around 100 miles below the earth's surface, before being carried up through volcanic activity. Diamonds can also be lab-grown today (chemically identical to mined diamonds), but “diamond”, mined or lab-grown, is always pure carbon, which is the key chemical difference from moissanite.

Moissanite vs diamond: full comparison

Everything you need to decide

To make this genuinely useful rather than just another spec sheet, here's everything you need to know — what moissanite actually is, why people choose it, who it suits, and exactly how much it costs.

What is the real difference between moissanite and diamond?

The core difference is composition and optics. Diamond is carbon; moissanite is silicon carbide. That difference in structure is what gives moissanite its higher refractive index (2.65–2.69 vs diamond's 2.42), meaning light bends more as it passes through the stone. In practice, this means moissanite throws off more visible rainbow-coloured flashes, sometimes called “disco ball” fire, especially in direct sunlight, while diamond tends to reflect more crisp, white brilliance. Neither is more “sparkly” in an absolute sense; they simply sparkle differently.

Why do UK shoppers choose moissanite over diamond?

Three reasons come up again and again: budget, ethics and practicality. Moissanite lets you get a larger, more eye-catching stone for the same spend a 1-carat moissanite might cost what a fraction-of-a-carat diamond would. It's lab-created, so there's no mining footprint and no ambiguity around sourcing. And because it's nearly as hard as diamond, it holds up to daily wear, gym sessions, gardening, washing up, without the anxiety that can come with a high-value natural stone.

Who is moissanite best suited for?

Moissanite tends to suit people who want maximum visual impact for their budget, who like the idea of a lower-impact, lab-created stone, and who wear their jewellery daily rather than saving it for occasions. It's also popular for statement pieces, pavé tennis bracelets, cross pendants or infinity necklaces, where a diamond equivalent would be prohibitively expensive for the same coverage of stones. Diamond, by contrast, tends to suit buyers prioritising long-term resale value, heirloom pieces, or those who specifically want a natural, billion-year-old stone.

When is the right time to choose moissanite instead of diamond?

Moissanite makes particular sense when you're buying for everyday wear rather than a single symbolic piece, when you want to maximise carat size on a set budget, when you're buying a first piece of fine jewellery and want to build confidence before investing more, or when the design itself calls for multiple stones (like a tennis bracelet or a pavé setting) where diamonds would push the price far beyond most budgets.

Where should you buy moissanite jewellery in the UK?

Look for retailers who are transparent about sourcing and grading. A genuine moissanite piece should come with clear information about the stone (often a GRA - Gemological Research Association,  report for loose or larger stones) and be set in a hallmark-compliant precious metal if it's marketed as gold or sterling silver. In the UK, any silver item over 7.78g or gold item over 1g legally requires hallmarking, so check that the metal itself, not just the stone, is properly documented. Buying from a retailer with clear product photography, honest carat and stone descriptions, and UK-based customer support makes the whole process far less stressful than a marketplace listing with no traceability.

How is moissanite graded and how can you tell it's genuine?

Moissanite is typically graded via a GRA (Gemological Research Association) certificate, which records carat weight, cut, colour, clarity and a unique report number, similar in spirit to how GIA certifies diamonds, though GRA is specific to moissanite and isn't a valuation document. To the naked eye, well-cut moissanite is very difficult to distinguish from diamond. A trained gemmologist can identify it through “doubling”, because of moissanite's optical properties, the facet edges at the back of the stone appear very slightly doubled when viewed at an angle through a loupe, an effect diamond doesn't produce.

How much does moissanite cost compared to diamond?

This is usually the deciding factor. A 1-carat moissanite typically runs around £220–£600 depending on cut and quality, while a comparable 1-carat diamond can range from roughly £3,000 to £12,000 or more depending on the four Cs (cut, colour, clarity, carat). That's a saving of roughly 85–90%, which is why moissanite has become so popular for pieces that use multiple stones, like tennis bracelets, pavé settings and cluster necklaces, where the diamond equivalent would be financially out of reach for most shoppers.

Is moissanite as durable as diamond for everyday wear?

Yes, for practical purposes. Diamond sits at 10 on the Mohs hardness scale (the hardest natural material known), and moissanite sits at 9.25, only slightly softer, and still harder than sapphire, ruby or emerald. In real-world terms, moissanite resists scratching extremely well and is considered fully suitable for rings, bracelets and earrings worn daily. If a piece ever looks dull, it's almost always down to everyday build-up like hand cream or soap residue rather than actual damage, a quick clean restores the sparkle.

Can people actually tell the difference between moissanite and diamond?

In everyday social situations, most people cannot tell the two apart with the naked eye, both stones are colourless (in their finest grades) and both throw serious sparkle. The difference becomes more noticeable in strong, direct sunlight, where moissanite's higher dispersion produces more visible flashes of rainbow colour, while diamond's brilliance stays whiter. Some people prefer moissanite's extra fire; others prefer diamond's more subdued sparkle, it genuinely comes down to personal taste.

Is moissanite a “fake” diamond?

No, and this is one of the most common misconceptions. Moissanite is not diamond simulant glass or cubic zirconia; it's a distinct mineral with its own chemical formula, its own hardness rating and its own name, first identified over a century ago. Reputable jewellers sell and describe moissanite as moissanite, not as a diamond. Think of it less as an “imitation” and more as a different gemstone that happens to compete visually in the same space as diamond, the same way sapphire or emerald compete with each other in the coloured-stone world.

Moissanite vs diamond vs cubic zirconia: what's the difference?

It's worth clearing this up, since the three are often confused. Cubic zirconia (CZ) is a much softer synthetic stone (around 8–8.5 on the Mohs scale) that tends to lose its sparkle and can look noticeably “glassy” over time, especially with daily wear. Moissanite sits well above CZ in hardness, brilliance and longevity, and holds its sparkle far better over years of use. If you've tried cubic zirconia jewellery in the past and found it disappointing, moissanite is a genuinely different tier of stone, not simply a rebrand.

Which should you choose: a decision guide by use case

Engagement rings and symbolic pieces: if long-term resale value, natural rarity or family tradition matter most to you, diamond remains the traditional choice. If you want maximum size and sparkle on a realistic budget, moissanite is an increasingly popular and well-regarded alternative,  including among UK jewellers who now offer it as a mainstream option rather than a “budget” one.

Everyday jewellery - necklaces, bracelets, stacking rings: moissanite tends to make more practical sense here. Pieces like pavé tennis bracelets, infinity pendants or cross necklaces use multiple small stones, and moissanite lets you enjoy a genuinely dazzling design without the cost of diamond multiplied across every stone in the setting.

Gifting: both work beautifully as gifts, but moissanite allows for a more generous, eye-catching design (a larger stone, a fuller pavé setting) at a price point that suits most gifting budgets, which is part of why sentimental pieces, from mother-and-child pendants to birthstone-style designs, are increasingly set with moissanite rather than diamond.

How to care for moissanite jewellery

• Clean it every one to two weeks with warm water, a drop of mild washing-up liquid and a soft toothbrush, focusing gently on the underside of the stone where oils collect
• Avoid direct contact with perfume, hairspray and chlorine, which can dull the surface over time
• Store pieces separately (a soft pouch or lined box) to prevent scratching from harder gemstones or other jewellery
• Remove rings and bracelets before heavy manual work, swimming or exercise to protect both the stone and the setting
• If set in sterling silver, occasional polishing with a silver cloth keeps the metal from tarnishing alongside the stone

Frequently asked questions