Moissanite vs Lab-Grown Diamond vs CZ: What's Actually Different

Four white stones sit behind almost every piece of iced jewelry you will see online, and the difference between them is the single most misrepresented thing in this category — usually by whoever is selling. So here is the comparison laid out with the actual measurements, plus the one thing the numbers do not tell you: how much difference the making of a piece matters at a given price.

The four materials, plainly

Start with what each one is, because three of the four get marketed as "diamond" in ways that are not true.

• Diamond (mined). Carbon, crystallized under pressure in the earth. Hardness 10 on the Mohs scale — the hardest material in common jewelry use. Refractive index 2.42, dispersion 0.044.
• Lab-grown diamond. Also carbon. Also a diamond. The only difference from a mined stone is where it formed — a growth chamber instead of a kimberlite pipe. Same hardness, same refractive index, same dispersion, because it is the same material. "Lab-grown" describes origin, not substance.
• Moissanite. Silicon carbide (SiC). It exists in nature only in trace amounts inside meteorite craters, so essentially all jewelry moissanite is lab-created. Hardness 9.25, refractive index 2.648–2.691, dispersion 0.104 — the highest fire of the four.
• Cubic zirconia (CZ). Zirconium dioxide (ZrO₂). Synthetic, no meaningful natural counterpart, developed in the 1970s as a diamond simulant. Hardness 8.0–8.5, refractive index 2.15–2.18, dispersion 0.058–0.066.

	Diamond	Lab-grown diamond	Moissanite	Cubic zirconia
What it is	Carbon	Carbon	Silicon carbide	Zirconium dioxide
Mohs hardness	10	10	9.25	8.0–8.5
Refractive index	2.42	2.42	2.648–2.691	2.15–2.18
Dispersion (fire)	0.044	0.044	0.104	0.058–0.066
Density (g/cm³)	3.51	3.51	3.22	5.6–6.0
Typical 1ct stone cost	Thousands	Hundreds to low thousands	Tens to low hundreds	A few dollars

Those figures are the standard published values for these materials; the moissanite numbers trace back to the reference measurements published in Gems & Gemology (GIA, Winter 1997, Vol. 33 No. 4).

What the numbers actually mean once you are wearing it

Three of those rows are the ones that matter in daily life.

Hardness decides how long it looks new

Household dust contains quartz, which sits at about 7 on the Mohs scale. Anything softer than that gets slowly abraded by ordinary contact. CZ at 8.0–8.5 is close enough to that threshold that the facet edges — the crisp lines that make a stone read as sharp — begin to round off with steady wear. Moissanite at 9.25 and diamond at 10 stay crisp far longer.

This is worth being precise about, because the internet is full of claims that CZ "clouds from the inside" or is "porous". A CZ stone does not cloud from within. It dulls because the surface picks up micro-scratches and holds onto skin oil and soap film, and once the facet edges have physically worn down, no cleaning brings the original sharpness back. That is a real and permanent limitation. It is just a wear issue, not a defect in the material.

Refractive index decides brightness

Higher refractive index means more light is bent back to your eye instead of passing through the stone. Moissanite returns more white light than diamond; CZ returns noticeably less than either. In a well-lit room this shows up as a difference in how "alive" the stone looks at a glance.

Dispersion decides fire

Dispersion is the separation of white light into color — the rainbow flash you see when a stone moves. Moissanite's 0.104 is more than double diamond's 0.044. Some people find that spectacular. Some find it too much and prefer the calmer white sparkle of a diamond. That is taste, not quality.

The CZ question: why a $59 piece can be excellent or unwearable

Here is the part most comparisons skip, and it is the part that decides whether you are happy with what arrives.

At the low end of the market, the stone is rarely what disappoints people. What disappoints people is everything around the stone.

Be clear about what a piece in this price band is. Plated base metal — copper or steel — with CZ. Nobody at $59 is selling you solid gold, and a seller who implies otherwise is the reason this category has a trust problem. What separates a good $59 piece from a bad one is four things:

• Stone grade and cut. CZ is produced in a wide range of grades and the cut geometry varies enormously. A well-proportioned stone with tight symmetry throws light properly. A cheap stone with sloppy angles looks flat no matter how bright the metal is.
• Setting work. This is where most of the money goes in a good piece. Micro-pavé set by hand, with each stone seated tight and its prongs finished down, means stones do not sit crooked, do not rattle, and do not fall out in the first month. Glue-set and loosely pronged work is the single most common failure point in cheap iced jewelry.
• Plating and finish. Plating thickness and surface prep decide how the color holds up. Thin flash over an unpolished base goes dull quickly; a properly prepped and plated surface lasts far longer, though any plated piece needs care — see our care guide.
• Inspection. Somebody has to actually look at each piece before it ships. Missing stones, uneven paving and loose clasps are caught at that step or they are not caught at all.

Five things to check before you buy any CZ piece

1. Is the stone named? "Cubic zirconia", "CZ", "AAA CZ" — good. "Diamond look", "diamond simulant", or nothing at all — ask.
2. Is the base metal named? Copper, brass, stainless steel, 925 silver. If it is not stated, it is probably the cheapest option available.
3. Is the plating named and is re-plating offered? Plating is a surface, not a permanent property. A seller who will not discuss re-plating is telling you something.
4. Can you see the setting in a close-up photo? Look at the prongs, not the sparkle. Crooked or sparse prongs are visible if the photo is honest.
5. Are the dimensions in millimetres? A photo on a screen has no scale. Width and length in real numbers are the only way to know what will arrive.

Every one of those answers is printed on our product pages, because the alternative — making the buyer find out on delivery — is exactly the experience that gives this price band its reputation.

What buyers actually said after delivery

Both of these came in on the same product — the 22mm iced out Cuban link, which starts at $59 as a 7 inch bracelet and runs up to a 24 inch chain. Neither customer was asked for a review and neither was offered anything for one, which is the only reason their messages are worth reading.

Review 1 — rose gold, 24 inch

She had already bought the 22mm Cuban in rose gold, 24 inch, in the CZ version. When it arrived she sent this:

"My rose gold 22mm chain arrived sick as fuck 🫶🫶🫶🫶🤍"

"Sick" is the slang — it means very good. She was not complaining about anything.

What happened next in the same conversation is the part worth reading twice. Having seen the piece in person, she asked what the identical design costs in moissanite. The answer was £458 for a 24 inch in rose gold. She said ok.

Put those two numbers side by side. The CZ version of this design is a two-figure purchase. The same width, same finish, same design in moissanite is £458. She did not go looking for the upgrade because the CZ piece had failed her — she went looking because it had worked, and she wanted the same thing in a stone that will still look like that in ten years.

Review 2 — Terry, two pieces

Terry has two pieces from us, a bracelet and a chain, one white gold and one yellow. He was out at the yard with his wife's horse when the parcel landed, sent photos nobody asked for, and when we asked whether we could use them he answered the question and kept going in the same breath:

"Mate the chain is fucking fire!!! And yea course ya can"

"I didn't expect it to look this good and thought it was some flimsy shit but boy was I wrong!!!"

Then, a few lines on, with nothing asked of him:

"Yea you have pulled through my man!! Thank you so much!!!"

When we said it sounded like he had been burned by other sellers before:

"Oh mate loads 😂"

He came back to it after 1am to give the specific reason, and it is the most useful sentence either of them wrote:

"Oh yea I know mate lol I've had stuff that turned me green 😂"

Only one of the two spelled out what he had been expecting, and it is worth sitting with: he assumed it would be flimsy, and he assumed the colour would come off on his skin. Not badly cut, not the wrong shade of gold — flimsy, and green. Those are the two failure modes this price band has actually earned, and he had been burned by both.

Notice what neither of them mentioned. Not the certificate, not the grading, not the refractive index. What they reacted to was whether the piece felt solid and looked right once it was on. That is the argument this whole article has been making: the stone is the easy part, the making is the whole game.

Two customers are not a survey, and we are not going to dress them up as one. But both paid full price, neither was offered a discount or a freebie for saying anything, and neither had a reason to be generous.

Why cheap plated jewelry turns your skin green

That last line deserves its own section, because almost everything sold in this price band gets it wrong and almost nobody explains it. "It's your body chemistry" is the explanation you will be given. It is not the explanation.

A green mark is not gold wearing off, and it is not a gold allergy. The green is copper salt. Copper and brass — the two base metals underneath nearly all plated jewelry — react with sweat and skin oils to form compounds that are green and rub onto skin. While the plating is intact and sealed, that reaction cannot happen, because the copper never reaches your skin in the first place.

So a green wrist is not a skin problem. It is a plating failure, and in practice it is one of three things:

• Too thin. Plating measured in fractions of a micron cannot survive the friction of a bracelet against a wrist, or a chain against a neck, for long.
• Plated over a rough base. A scratched or unpolished surface needs more plating to cover it. Plate it to the same thickness as a polished piece and the high points end up with almost nothing on them.
• No barrier layer. A colour plate applied straight onto copper has no separation between the two metals. The barrier underneath is what keeps the base from ever reaching your skin.

All three are decided before the piece is ever gold-coloured. Polish the base, lay down a barrier, plate the colour, seal it. Skip any one step and you get a piece that looks identical in the product photo and marks your collar within a month. That is what the plating line in the list above is actually buying — not a shinier yellow, a longer life.

Nickel is a different problem and a real one. It causes contact dermatitis — redness, itching, sometimes blisters — rather than a green stain, and for people who react to it no amount of care helps. If that is you, ask for nickel-free before you buy, not after.

One honest caveat, because this article is not going to pretend otherwise: every plated piece wears through eventually at the points taking the most friction — the inside of a bracelet, wherever a clasp rubs. That is physics. What decent manufacturing buys you is years instead of weeks, and wear that fades gradually rather than flaking off in patches.

The pieces on this site are triple-plated over a copper core. Ask any seller — including us — exactly what that stack is before you buy, and treat a seller who cannot answer the question as having answered it.

So which one should you buy

Match the material to the job, not to a ranking.

• Something worn daily for decades. Diamond or moissanite. Both hold their surface. Moissanite costs a fraction of a lab-grown diamond of the same size and throws more fire; a lab-grown diamond is a diamond and reads like one under any inspection.
• A statement piece you wear hard, indoors and out. Moissanite is the sweet spot — 9.25 hardness, more brilliance than anything else on this list, and priced so you can buy a real width instead of a thin chain.
• Maximum visual impact per dollar, worn in rotation. CZ, bought well. You are accepting that the surface will dull over years of heavy wear. In exchange you get the full iced look at a price that does not require a decision. Buy from someone who names the stone, names the metal, and shows you the prong work.
• Investment or resale. None of the above except a mined diamond, and honestly not even then.

The one claim we will not make

You will see sellers advertising stones on the basis of what they "pass" on a tester. We do not do that, and here is why: a basic thermal tester reads moissanite as diamond because silicon carbide conducts heat similarly. That is a limitation of a cheap instrument, not a feature of the stone. Any stone worth buying should be identified plainly on the page you buy it from — the material, the grade, the metal, the measurements. If you have to rely on a tester result to feel good about a purchase, the listing has already failed you.

FAQ

Is moissanite a diamond?

No. Moissanite is silicon carbide; a diamond is carbon. They are different materials with different hardness, different refractive index and different dispersion. Moissanite is its own gemstone, not a diamond substitute that failed to qualify.

Is a lab-grown diamond a real diamond?

Yes. It is carbon with the same crystal structure and the same optical and physical properties as a mined diamond. The distinction is origin, not material. What it is not is cheap — a lab-grown diamond still costs hundreds to thousands per carat.

Does CZ go cloudy and can it be fixed?

A CZ stone does not cloud internally. It dulls because the surface accumulates micro-scratches from contact with harder grit, and holds onto oil and soap film. Cleaning restores the surface film; it cannot restore facet edges that have physically worn down. On a piece worn occasionally and kept clean, this takes a long time. On something worn daily against grit, expect visible dulling within a few years.

Can you tell CZ from a diamond by eye?

Across a room, not reliably — that is the entire reason CZ exists. Close up, yes: a diamond has a cooler, whiter sparkle, CZ has a softer and slightly glassier look, and a loupe reveals the difference immediately. If the question you actually care about is "will people notice", the honest answer is that almost nobody inspects your jewelry that closely, and the people who do will ask rather than assume.

Why is your moissanite so much more than your CZ?

Because silicon carbide costs more than zirconium dioxide, is harder to cut, and needs different setting work. The moissanite collection carries GRA documentation per stone. The cubic zirconia pieces do not, and no seller can honestly provide one — GRA certifies moissanite only, and there is no equivalent document for zirconium dioxide. If a listing advertises a GRA certificate on a zirconia piece, that certificate is not describing what you are buying.

Why did my last chain turn my neck green?

Because the plating wore through or was never properly sealed, and sweat reached the copper or brass underneath. Copper salts are green and transfer to skin easily. It is a manufacturing and wear problem, not an allergy and not "your body chemistry" — changing your soap will not fix it, a properly barrier-plated piece will. The stone has nothing to do with it.

Can a $59 iced out chain actually be any good?

Yes, on the same terms as any plated piece: the stone will not be the part that disappoints you, the making will. Judge it on prong density, whether the base metal and plating are named, whether re-plating is offered, and whether the dimensions are given in millimetres. A $59 piece that answers those four questions is a better buy than a $150 piece that dodges them.

Which looks more expensive in person?

Width and setting density, more than material. A 15mm fully paved CZ chain reads as more expensive from across a room than a thin moissanite one, because presence is about mass and coverage. Material decides how it looks in five years, not in five seconds.

Where to start

If the two messages above are the reason you are still reading, start with the piece they were both talking about: the 22mm iced out Cuban link — 5A cubic zirconia on a triple-plated copper core, $59 as a 7 inch bracelet up to a 24 inch chain. Same design, same finish, available in white gold, yellow gold and rose gold.

If you want the durability argument settled instead, go straight to the VVS moissanite collection — or the piece that shows the material off best, the 22mm moissanite Cuban link necklace, which is the exact upgrade the customer above asked about.

Two more honest entry points if you want to test the price band first: the colorful gemstone cross pendant at $51 and the multicolor star choker at $56. Our full material commitments are on the our promise page.