Moissanite vs Cubic Zirconia: Which Is Better for an Engagement Ring?

Moissanite is harder, more brilliant and far more durable than cubic zirconia. GIA rates moissanite 9.25 on the Mohs scale and cubic zirconia 8.5, and GIA notes that colourless CZ yellows over time. Cubic zirconia costs much less, so it suits fashion jewellery, while moissanite is built to be worn every day for decades as an engagement ring.

If you are shopping for an engagement ring in Canada on a budget, moissanite and cubic zirconia will both come up, often in the same search results and sometimes described with the same words. They are very different stones. One is a serious diamond alternative that people wear for life. The other is a low-cost simulant that looks great on day one and wears out. Here is how they compare, what to look for when you shop, and how to tell them apart.

Moissanite vs cubic zirconia at a glance

	Moissanite	Cubic zirconia (CZ)	Diamond (for reference)
What it is	Lab-made silicon carbide	Lab-made zirconium dioxide	Carbon (natural or lab-grown)
Hardness (Mohs)	9.25	8.5	10
Fire	More than twice diamond's	Slightly more than diamond	Benchmark
Brilliance	Slightly more than diamond	Less than diamond	Benchmark
Long-term appearance	Stays colourless to near-colourless	Colourless CZ yellows over time	Stable
Durability	Excellent toughness	Can be somewhat brittle	Excellent
Reads as diamond on a basic thermal tester?	Yes	No	Yes
Typical use	Engagement rings, everyday fine jewellery	Fashion and costume jewellery	Engagement rings, fine jewellery

Hardness, fire, brilliance and colour notes are from GIA's introduction to imitation diamonds and its buyer's guide to diamond alternatives.

What is the difference between moissanite and cubic zirconia?

Both are made in a lab, and both can look like a diamond across a room. That is about where the similarities end.

Moissanite is silicon carbide. Natural moissanite is extremely rare, so every moissanite in jewellery is lab-made. GIA notes that colourless synthetic moissanite became popular as a diamond imitation in the late 1990s. It is the second-hardest stone commonly used in jewellery after diamond, and GIA describes its toughness as excellent, which is why it can be set in an engagement ring and worn every day.

Cubic zirconia is a crystalline form of zirconium dioxide, introduced in the late 1970s. It is inexpensive to produce, usually flawless to the eye, and can be made in almost any colour. That is why it shows up in so much fashion jewellery. It is softer than moissanite, and GIA says colourless CZ yellows over time and can be somewhat brittle.

Which sparkles more, moissanite or cubic zirconia?

Moissanite, by a clear margin. Sparkle has two parts: brilliance, the white light returned to your eye, and fire, the flashes of rainbow colour. According to GIA, moissanite has slightly more brilliance than diamond and more than twice the fire. CZ has slightly more fire than diamond but less brilliance.

In practice, a fresh CZ looks bright and a little glassy. Moissanite looks lively, with colourful flashes that are more obvious in sunlight and in larger stones. GIA notes that in stones of a carat or more, the strong fire can read as a "disco ball" effect. Some people love it. If you want something closer to a diamond's look, a well-cut moissanite in a moderate size, or an oval or elongated shape, keeps the fire in balance. Our moissanite vs diamond guide covers that comparison in detail.

Does cubic zirconia get cloudy or yellow?

Yes, over time. GIA states that colourless CZ yellows with age. CZ is also softer, so the facet edges pick up scratches and wear from daily contact with harder materials. Once the facets are dulled and the surface scuffed, the stone holds dirt and looks cloudy even after cleaning.

Moissanite does not have that problem. At 9.25 on the Mohs scale, very little in daily life will scratch it, and its colour is stable. It still gets dirty like any stone, since lotion and skin oils cling to the surface, but a clean moissanite looks the same years later as it did on the day you proposed. Our moissanite care guide explains how to keep it bright.

Is cubic zirconia good enough for an engagement ring?

For a short-term or placeholder ring, it can be. Some couples propose with a CZ and pick the real ring together, or wear a CZ while travelling. For a ring someone will wear every day for years, we do not recommend it. An engagement ring takes knocks against desks, steering wheels, car doors and countertops. CZ's lower hardness and tendency to be brittle mean chips and worn facets, and the yellowing is not something cleaning can fix.

There is also the setting to think about. A CZ is often set in plated base metal or sterling silver, which wears too. Moissanite engagement rings are typically set in solid gold or platinum, so the whole ring is built to last. If you are weighing metals, see our guides to 14K vs 18K gold and platinum vs white gold.

How can you tell moissanite from cubic zirconia?

A few signs can help, though a jeweller's tester is the only reliable answer.

• Look at the back facets with a loupe. GIA explains that moissanite is doubly refractive, so you see a doubled image of the back facet edges when you look through the stone at an angle. CZ is singly refractive and does not show this.
• Watch the colour flashes. Moissanite throws strong rainbow fire, especially in sunlight. CZ is bright but less fiery.
• Check the age and wear. An older CZ often shows scratched, rounded facet edges and a slightly yellow or cloudy look. Moissanite holds sharp edges.
• Use a thermal diamond tester, carefully. In GIA's Gems & Gemology, gemmologists reported that thermal probes react to synthetic moissanite as if it were diamond. CZ does not register as diamond on those testers. So a thermal "diamond" reading tells you the stone is not CZ, but it does not prove the stone is a diamond. A jeweller with a dedicated moissanite tester can settle it.

If you are buying online, ask the seller what the stone is in writing. A listing that says "simulated diamond" or "diamond-look" without naming the material is often CZ. Our guide on buying a moissanite ring online in Canada lists the questions to ask.

Is moissanite worth the extra cost over cubic zirconia?

For an engagement ring, yes. The price gap is real: CZ is one of the cheapest stones on the market, and a moissanite engagement ring in solid gold costs far more. What you are paying for is a stone that keeps its look for a lifetime and a setting made to be resized, repaired and worn daily. Spread over years of wear, that is the better value.

Where CZ makes sense:

• A travel ring or a stand-in while the real ring is being made.
• Fashion jewellery you will wear occasionally.
• Testing a shape or carat size on the hand before committing.

Where moissanite makes sense: any ring meant to be worn every day, especially an engagement ring, and anyone who wants a large centre stone without lab or natural diamond prices. If you are deciding between moissanite and a lab diamond instead, read our moissanite vs lab diamond comparison.

Shopping for a moissanite engagement ring in Toronto or anywhere in Canada

At Toronto Fine Jewelry, every engagement ring is handcrafted to order in solid gold or platinum, and moissanite engagement rings start at $1,050 CAD. We also make rings with lab-grown diamond and coloured gemstone centre stones. Casting, setting and polishing take 4 to 6 weeks from design approval, so if you are planning a Christmas proposal, approve your design by November 13, 2026; for Valentine's Day, by January 3, 2027.

Frequently asked questions

Is moissanite better than cubic zirconia?

For an engagement ring, yes. Moissanite rates 9.25 on the Mohs scale against 8.5 for CZ, has more brilliance and fire, and keeps its colour. GIA notes that colourless CZ yellows over time.

Will moissanite pass a diamond tester?

It will pass a basic thermal tester, because thermal probes react to moissanite as they do to diamond. Cubic zirconia does not. A jeweller's dedicated moissanite tester can tell moissanite from diamond.

Does moissanite get cloudy like cubic zirconia?

No. Moissanite is hard enough to resist the scratches that dull CZ, and its colour is stable. Any cloudiness on a moissanite is surface dirt or oil, which comes off with warm water, mild soap and a soft brush.

Can you use cubic zirconia in an engagement ring?

You can, but it is best as a temporary or travel ring. CZ is softer, can be brittle and yellows with age, so it does not hold up to daily wear for years the way moissanite or diamond does.

Is moissanite a fake diamond?

No. Moissanite is its own gemstone, silicon carbide, with different properties from diamond. It is a diamond alternative, and a reputable seller will always identify it as moissanite.