Cubic Zirconia vs Moissanite: How to Choose the Right One

Moissanite is the more durable, more brilliant and longer-lasting choice; cubic zirconia (CZ) is the far cheaper one. Moissanite rates about 9.25 on the Mohs hardness scale against roughly 8 to 8.5 for CZ, so CZ scratches and dulls sooner with daily wear, and GIA notes it can yellow over time. For a ring you will wear every day for years, moissanite usually wins; for fashion jewellery, travel pieces or occasional wear, CZ is a sensible budget pick.

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This guide compares cubic zirconia vs moissanite on hardness, sparkle, weight, how each ages, how testers and jewellers tell them apart, and what you are really paying for, so you can choose a budget alternative to diamond without regret.

At a glance

• Two different materials. CZ is zirconium oxide; moissanite is silicon carbide. Both are made in laboratories for jewellery, and neither is a diamond.
• Moissanite is harder. About 9.25 on the Mohs scale versus around 8 to 8.5 for CZ, so moissanite keeps crisp facet edges for much longer.
• Sparkle differs. Moissanite shows strong rainbow fire; CZ has a softer, slightly glassier look and less brilliance than diamond.
• CZ is heavier. It is much denser than diamond or moissanite, so a CZ of the same size weighs noticeably more.
• Testers tell them apart. CZ fails a basic thermal diamond tester; moissanite can pass one and needs an electrical-conductivity or multi-tester.
• Cost versus lifespan. CZ costs very little but may need replacing; moissanite costs more up front but is built for decades of wear.

Cubic zirconia vs moissanite: side-by-side

Feature	Cubic zirconia (CZ)	Moissanite	Diamond (for reference)
Material	Zirconium oxide, laboratory-made	Silicon carbide, laboratory-made	Carbon (natural or lab-grown)
Mohs hardness	About 8 to 8.5	About 9.25	10
Look	Bright, a little more fire than diamond but less brilliance	Strong rainbow fire, about two and a half times diamond’s dispersion	Balanced white and coloured sparkle
Refraction	Singly refractive	Doubly refractive (facet edges can look doubled)	Singly refractive
Weight for the same size	Much heavier (roughly 1.7 times diamond’s density)	Slightly lighter than diamond	Baseline
Ageing with daily wear	Scratches, facet edges round off, can look cloudy; may yellow over time	Keeps polish and sparkle for decades with cleaning	Keeps polish; can still chip from a hard knock
Thermal diamond tester	Fails (conducts heat poorly)	Can pass (conducts heat well)	Passes
Grading	No standard grading	Colour and clarity usually graded by the producer or seller	Independent laboratory reports available
Relative price	Lowest	Moderate	Highest (natural), lower for lab-grown
Resale	Essentially none	Essentially none	Some for natural; weak for lab-grown

What each stone actually is

Cubic zirconia

Cubic zirconia is a crystalline form of zirconium oxide made by melting zirconium oxide powder at very high temperature and letting crystals grow as it cools. GIA dates its introduction as a diamond imitation to the late 1970s, and it quickly became the most common inexpensive diamond look-alike because it is colourless, clean and cheap to produce. It is a perfectly honest material when it is sold as CZ.

Moissanite

Moissanite is silicon carbide. Natural moissanite is extremely rare and occurs as tiny grains, so every moissanite sold in jewellery is laboratory-made. GIA notes that colourless synthetic moissanite became popular as a diamond imitation in the late 1990s. It sits between CZ and diamond: much tougher-wearing than CZ, but with a distinctive fiery look of its own. Our moissanite vs diamond comparison covers how it stacks up against the real thing.

Durability: which one lasts?

This is the biggest practical difference. Everyday dust contains quartz, which is about 7 on the Mohs scale. Any stone harder than that resists scratching from ordinary grit, but the margin matters over years of wear. CZ, at around 8 to 8.5, sits only a little above quartz, so its surface gradually picks up fine scratches and its facet edges soften. Over time that makes a CZ look duller or slightly cloudy, even after cleaning, and GIA notes that CZ can also yellow over time.

Moissanite, at about 9.25, is second only to diamond among popular ring stones. It keeps sharp facets and its polish for decades, and its sparkle comes back fully with a clean. Neither stone is indestructible: both can chip if knocked hard against stone, metal or a door frame, so a protective setting helps for active hands. Our guide to ring settings explains which styles shield the stone best.

In practical terms: a CZ engagement ring worn every day can show visible wear within a few years, depending on how it is worn, while moissanite is designed to be a lifetime stone. For earrings and pendants, which take far fewer knocks, CZ lasts much longer.

Sparkle and colour: how they look

Moissanite has a higher refractive index and much stronger dispersion than diamond, so it throws more rainbow-coloured flashes, especially in sunlight and in larger stones. Some people love that lively look; others find it reads as “not diamond” at a glance. Moissanite is also doubly refractive, so looking through the top at an angle you may see the back facet edges doubled.

CZ has slightly more fire than diamond but less brilliance, giving a bright but softer, glassier look. Fresh CZ is usually very white and clean, which is why it can look convincing in new fashion jewellery. Moissanite colour has improved a great deal, but colour grades are generally assigned by the producer or seller rather than an independent laboratory, so judge the stone in daylight and indoor light rather than relying on a letter alone.

Weight and size

CZ is much denser than diamond and moissanite. That means a CZ of the same diameter weighs more, and a CZ sold by carat weight looks smaller than a diamond of the same weight. Moissanite is slightly lighter than diamond, so many sellers describe moissanite by millimetre size or “diamond-equivalent” weight. When comparing listings, compare millimetre dimensions, not carats.

How to tell cubic zirconia from moissanite

1. Look for doubling. Under a 10x loupe, view the stone through the top at a slight angle. Doubled back facet edges point to moissanite; CZ and diamond show single edges.
2. Check for wear. Rounded facet edges, fine scratches on the table and a dull surface on an older stone suggest CZ.
3. Watch the fire. Intense rainbow flashes, especially in a stone of a carat or more, suggest moissanite.
4. Feel the weight. A loose CZ feels heavy for its size compared with moissanite.
5. Use the right tester. A thermal diamond tester will flag CZ as not diamond, but can read moissanite as diamond. A multi-tester that also checks electrical conductivity is needed to separate moissanite.
6. Read the paperwork. A receipt or certificate should name the material. A diamond grading report applies only to diamonds.
7. Ask a professional if it matters, for example before selling, insuring or valuing a piece.

Home checks only point you in a direction. Our guide on how to tell if a diamond is real ranks the at-home checks and explains when to get a jeweller’s opinion.

Price: what you are paying for

CZ is the cheapest convincing diamond look-alike; loose stones and fashion pieces are priced mostly for the metal and workmanship, not the stone. Moissanite costs considerably more than CZ, though still far less than a natural diamond of the same size and usually less than a lab-grown diamond. Exact prices vary by size, cut quality, colour, brand and country, and prices change, so compare the same millimetre size and shape when you shop.

Think in cost per year of wear. If a CZ ring needs replacing after a few years of daily wear, buying it two or three times may approach the price of one moissanite. For occasional jewellery, the CZ saving is real and sensible. If you are weighing up a genuine diamond as well, our lab-grown diamond buyer’s guide explains where that option fits.

Neither CZ nor moissanite has a meaningful resale market, so buy either one for the joy of wearing it, not as something to sell later.

Which should you choose?

Your situation	Better fit	Why
Engagement or everyday ring for years	Moissanite	Hardness keeps it looking new far longer
Fashion jewellery or trend pieces	CZ	Low cost suits pieces you may change often
Travel or holiday stand-in for a valuable ring	Either	Both are cheap to replace; moissanite lasts longer
Trying a shape or size before buying a diamond	CZ	An inexpensive way to test how a look suits you
Earrings or pendant worn occasionally	CZ or moissanite	Less wear means CZ holds up well
You dislike strong rainbow sparkle	Consider a diamond or a different gemstone	Moissanite’s fire is its signature

If neither feels right, there are coloured stones that wear well too; our guide to the best gemstones for engagement rings compares the options.

Buying checklist

• The listing or receipt names the material clearly: “cubic zirconia”, “moissanite” or “simulated diamond”.
• Size is given in millimetres, not just carats.
• For moissanite, you know who assigned any colour grade.
• The metal is stated (solid gold, sterling silver, plated), since the setting often costs more than the stone.
• The setting suits how often and how hard the piece will be worn.
• Returns and warranty terms are in writing before you pay.

Common mistakes

• Treating CZ as a lifetime engagement stone. It can be, if you accept replacing it, but expect visible wear with daily use.
• Comparing by carat weight. CZ’s density makes carat comparisons misleading; compare millimetres.
• Trusting a basic diamond tester. A thermal-only tester can mark moissanite as diamond.
• Paying gold prices for plated metal. Many budget pieces are plated; check the metal stamp and description. Our guide to sterling silver gemstone jewellery covers what to look for.
• Expecting resale value. Neither stone has a real second-hand market.
• Accepting vague labels. Under the US Federal Trade Commission’s Jewelry Guides, a laboratory-made or imitation stone should not be sold under a gemstone name without a clear qualifier such as “simulated” or “imitation”; rules elsewhere differ, but clear labelling is a good sign of an honest seller.

Caring for either stone

Both clean well with warm water, a drop of mild washing-up liquid and a soft brush. Take rings off for gym work, gardening and cleaning with chemicals, and store pieces separately so harder stones do not scratch softer ones; CZ in particular can be scratched by diamond or moissanite jewellery in the same pouch. Our guide to cleaning diamonds safely covers the same gentle routine.

Sources this guide draws on: GIA’s introduction to diamond simulants and imitation gem materials, standard gemmology references on synthetic moissanite and cubic zirconia, gem tester explanations from gemmological suppliers, and the US Federal Trade Commission’s Jewelry Guides.

Frequently asked questions

Is moissanite better than cubic zirconia?

For durability and long-term sparkle, yes: moissanite is harder, resists scratching and keeps its polish for decades. CZ is better only on price, which makes it a good choice for fashion or occasional jewellery.

Does cubic zirconia get cloudy?

Over years of wear, CZ can look cloudy or dull because its surface scratches and its facet edges wear down, and GIA notes it can yellow over time. Dirt and lotion also dull any stone, so clean it first before deciding it has clouded.

Can a jeweller tell moissanite from cubic zirconia?

Yes, usually quickly. Moissanite’s doubled facet edges, strong fire and tester results differ clearly from CZ, which is singly refractive, heavier for its size and fails a thermal tester.

Will moissanite or CZ pass a diamond tester?

CZ fails a standard thermal diamond tester. Moissanite can pass a thermal-only tester because it conducts heat well, so a multi-tester with an electrical-conductivity check is needed to separate it from diamond.

Is moissanite vs CZ worth the extra cost?

For a ring worn every day, usually yes, because it is far less likely to need replacing. For pieces worn now and then, the extra cost is harder to justify.

Both stones are honest choices when they are labelled honestly. Decide how often the piece will be worn and how long you want it to look new, then let that answer guide the choice between low cost and long life.