Moissanite vs Cubic Zirconia: How Each One Ages After a Year

On day one, in a photograph, under a shop light, moissanite and cubic zirconia can be hard to tell apart. Both are white, both throw light, and both are lab-made. That is why the comparison confuses people.

The difference does not show up on day one. It shows up somewhere around month nine, and by the end of a year of daily wear it is obvious across the room. Here is what actually happens to each stone, and — because it is true — the situations where CZ is the smarter thing to buy.

They are two different materials, not two grades of the same thing

Moissanite is silicon carbide — the same compound Henri Moissan first identified in fragments of an Arizona meteor crater in 1893. Natural moissanite is vanishingly rare, so every stone in jewelry today is grown in a lab under controlled heat and pressure. The result is a hard, non-porous, chemically stable crystal.

Cubic zirconia is zirconium dioxide, stabilized with a small amount of yttrium or calcium so it holds a cubic crystal structure. It was developed in the 1970s specifically as an inexpensive diamond simulant, and it is very good at that job when new.

Neither is a fake version of the other. They are separate materials with different physical properties, and those properties are what decide how each one holds up.

Hardness: 9.25 versus 8 to 8.5

On the Mohs scale, moissanite sits at about 9.25. Cubic zirconia sits at about 8 to 8.5. Diamond is 10.

Written down, that gap looks small. It is not, for two reasons.

First, the Mohs scale is not linear. It is an ordered list of what scratches what, not a measure of how much harder. The absolute jump in scratch resistance between 8.5 and 9.25 is much larger than the numbers suggest.

Second, and this is the part that decides everything: ordinary household dust contains quartz, and quartz sits at 7 on the Mohs scale. Grit on your hands, dust on a countertop, sand on a beach towel, the particles in the air of any room — a lot of it is quartz. At 8 to 8.5, cubic zirconia is close enough to that number to be slowly abraded by everyday grit. At 9.25, moissanite is comfortably clear of it and essentially unbothered.

That single fact is why one stone dulls and the other does not.

Brilliance and fire

Two numbers describe how a stone handles light.

Refractive index is how strongly the stone bends light, which drives raw brightness. Moissanite is about 2.65 to 2.69. Diamond is 2.42. Cubic zirconia is about 2.15 to 2.18. Moissanite is the brightest of the three; CZ is the least bright, which is why it can look slightly glassy next to the others even when brand new.

Dispersion is how much the stone splits white light into colored flashes — the "fire". Moissanite is about 0.104, roughly two and a half times diamond's 0.044. Cubic zirconia is around 0.058 to 0.066, so it sits between the two.

The photograph at the top of this page is the difference in one frame. The moissanite on the left returns light cleanly through crisp facets and throws visible colored flashes. The cubic zirconia on the right is the same size and shape, and reads flatter and milkier.

In practice: moissanite reads as intensely bright with noticeable rainbow flashes, especially in sunlight and in larger stones. CZ reads white and bright when new but flatter, with less of that darting flash. If you have ever thought a stone looked "like glass" rather than like a gem, low refractive index is usually what you were reacting to.

Weight, which nobody mentions

Cubic zirconia is dense — roughly 5.6 to 6.0 grams per cubic centimeter. Moissanite is about 3.21. For the same physical size, a CZ stone weighs close to twice as much as a moissanite one.

On a small stud it is irrelevant. On a 12mm cluster, a wide tennis chain, or a large pendant it is not: the CZ version will hang heavier, pull more on a piercing, and feel less comfortable over a long day. It also means carat weight is a misleading way to compare the two, since a 1-carat CZ is visually much smaller than a 1-carat moissanite.

After a year of daily wear

This is the section that matters.

What happens to cubic zirconia

Wear is cumulative and physical. Over months of contact with grit, fabric, other jewelry and cleaning products, the sharp edges where facets meet begin to soften and round. The mirror polish on each facet picks up fine surface abrasion. Light no longer enters and leaves cleanly, so the stone scatters instead of reflecting.

The result reads as haze. It usually starts near the girdle and on the top facets, and it is worst on rings and bracelets, which take the most contact. Many CZ stones also warp slightly in color over time — a faint gray or yellow cast, sometimes from surface damage, sometimes from the stone absorbing oils and residue.

The important point: this damage is physical, so cleaning does not fix it. Once the polish is gone, it is gone. The piece has not got dirty; it has worn out. Most CZ jewelry worn every day looks tired somewhere between one and three years in, and the usual outcome is replacement.

What happens to moissanite

Very little. At 9.25 the facet edges hold, the polish stays, and the refractive index that produces the brightness is a fixed property of the crystal rather than a coating that can wear away. A moissanite stone is chemically and optically the same stone after a year, or after ten.

Moissanite pieces do go dull — but for a different, reversible reason. A film of skin oils, hand cream, sunscreen and hairspray builds up on the surface and behind the setting, and that film scatters light exactly the way surface damage does. The difference is that it washes off in five minutes with warm water, a drop of dish soap and a soft brush. We covered this in detail in does moissanite get cloudy.

So: dull CZ is usually damage. Dull moissanite is almost always dirt.

What happens to the metal, either way

Worth saying plainly, because it gets blamed on the stone. Both materials are usually set in .925 sterling silver, and silver tarnishes regardless of what is set in it. A darkened setting makes any stone look duller by contrast. That part is reversible on both — see how to care for sterling silver.

Where cubic zirconia is honestly the better buy

We sell moissanite, so take this in the spirit it is meant: CZ is not a bad material. It is a material with a short service life, and there are plenty of situations where a short service life is exactly what you need.

• Costume and trend pieces. Something tied to a specific look you will wear a handful of times does not need to last ten years. Paying for durability you will not use is just paying more.
• One event, one very large stone. Cost scales fast with size. If you want an enormous stone for a single night and the look is the whole point, CZ delivers it for a fraction of the price.
• Testing a style before you commit. Not sure whether a shape, a stone size or a ring silhouette suits you? A cheap CZ version is a legitimate way to find out before spending properly.
• High-risk wear. Travel where you would rather not carry anything valuable, festivals, a first pair for a young teenager, anything that might get lost, sat on or left in a hotel. Losing CZ is annoying. Losing something better is worse.
• Unusual colors on a budget. CZ comes cheaply in a very wide color range, so for a specific bright shade in a fun piece it can simply be the practical option.
• When the real alternative is nothing. If the choice is a CZ piece now or an empty jewelry box, wear the CZ piece.

Where moissanite is worth the difference

• Anything you will wear every day. Studs, an everyday chain, a bracelet you never take off. This is where CZ's wear rate does its damage and where moissanite pays for itself.
• Anything with meaning attached. An engagement piece, an anniversary gift, something you want to still own in fifteen years. A stone you have to replace is a poor carrier for that.
• Anything worn on the hands. Rings and bracelets take more abrasion than every other category combined.
• Anything you want to look expensive up close. The refractive index gap is visible when someone leans in.

The clearest way to think about price is cost per year rather than cost. A CZ pair of studs replaced three times over five years, plus the small irritation each time, lands close to one moissanite pair that is still bright at the end of it — and you spent those five years wearing the better stone.

How to tell what you are actually being sold

"Simulated diamond", "diamond-like", "iced" and "lab stone" are marketing terms and can mean anything. Before you buy, look for four specifics:

1. The material named outright — silicon carbide moissanite, or cubic zirconia. If a listing will not say which, assume the cheaper one.
2. A Mohs figure. 9.25 is moissanite. 8 to 8.5 is CZ.
3. Stone grading. Moissanite is graded for color and clarity like a diamond — ours is D-color, VVS1, explained in what is VVS moissanite. CZ is generally not graded, because there is little variation to grade.
4. The metal. A quality stone in plated base metal is a false economy; the setting fails before the stone does. Look for a .925 stamp or a solid gold karat mark.

One thing a tester will not settle for you: moissanite passes a standard thermal diamond tester because it conducts heat much like diamond does, while CZ does not. It takes a dual-probe moissanite tester to separate moissanite from diamond. The full explanation is in does moissanite pass a diamond tester.

Frequently asked questions

Is moissanite better than cubic zirconia?

For anything worn regularly, yes. Moissanite is harder at 9.25 Mohs against CZ's 8 to 8.5, brighter with a refractive index of 2.65 to 2.69 against 2.15 to 2.18, and it does not develop the permanent surface haze that CZ does. For short-term or costume pieces, CZ can be the sensible choice.

How long does cubic zirconia last?

Worn daily, most CZ starts to visibly haze somewhere between one and three years as facet edges abrade and the polish wears. Worn occasionally and stored well, it lasts considerably longer.

Does cubic zirconia turn cloudy permanently?

Yes, once the surface polish is abraded. That is physical damage rather than dirt, so cleaning will not restore it. Moissanite dulling, by contrast, is a removable film of oils and residue.

Can you tell moissanite and CZ apart by looking?

When both are new it is difficult. Moissanite is noticeably brighter with more colored fire, and CZ is roughly twice as dense so it feels heavier for its size. After a year of wear the difference is obvious: the CZ will have gone hazy.

Is moissanite worth the extra cost over cubic zirconia?

For daily-wear and sentimental pieces, yes — on a cost-per-year basis it usually works out cheaper, because CZ needs replacing. For a one-off costume piece or a single event, it may not be.

Which is closer to a real diamond?

It depends on the property. CZ is closer to diamond in dispersion, so its fire looks more diamond-like. Moissanite is far closer in hardness and durability and is brighter than diamond. For a stone that behaves like a diamond over years of wear, moissanite is much closer.

See moissanite in real settings

Every Jamilah Jewels piece uses D-color, VVS1 lab-grown moissanite set in .925 sterling silver. Start with the cluster earrings, the tennis chains or the tennis bracelets, or browse the full collection. Free insured shipping and 30-day returns on every order.

Pick the stone that stays bright

Both are the daily-wear pieces where moissanite earns its keep. See the full collection for more.