Cubic Zirconia vs Moissanite: Two Simulants Compared

Cubic zirconia (CZ) and moissanite are both diamond simulants: stones made to look like diamond without being diamond. They sit at very different levels. CZ is the cheapest convincing white stone there is, which is why it fills most low-priced iced chains, rings and watch bezels. Moissanite costs more, wears much better and fools more testers.

If a piece is for a costume look, a photo shoot or a one-season trend, CZ does the job. If you want a simulant you can wear every day for years, moissanite is the better buy. If you want the real thing, neither: look at lab-grown or natural diamond.

Both stones are manufactured. Neither is mined for jewelry.

Cubic zirconia is zirconium dioxide melted at very high heat with a stabilizer, usually yttrium oxide, then cooled into large crystals. The method, called skull melting, was scaled up in the Soviet Union in the 1970s, and production is now so large that CZ costs pennies per carat in bulk. It can be made in almost any color by adding trace elements.

Moissanite is silicon carbide. Making clear, gem-quality crystals took decades of work, and colorless moissanite only reached jewelry counters in the late 1990s. Growing it is slower and more expensive, and cutting it takes more time because it is so hard. That is the main reason it costs several times more than CZ.

The production gap shows in the finished stones. CZ is often machine-cut fast in huge batches, with rounded facet junctions even when new. Better moissanite is cut more precisely, which helps it look sharper on day one.

Sparkle depends on sharp, polished facets. Anything that rounds those facet edges or scratches the top kills the light return. Household dust contains quartz, which is about 7 on the Mohs scale. A stone harder than 7 resists it, and the further above 7, the better.

• CZ at 8 to 8.5 resists dust at first, but daily knocks against counters, keys and other jewelry wear its facet junctions down. After a year or two of constant wear the edges look soft and the stone starts to look glassy.
• Moissanite at 9.25 is harder than ruby and sapphire. It takes years of hard wear before the edges show anything.

On iced pieces with dozens or hundreds of small CZ stones packed together, the stones also rub against each other and against the metal. That is a big reason cheap iced chains lose their flash quickly.

People say CZ "gets cloudy." What usually happens is a mix of two things. First, the scratched surface scatters light instead of reflecting it. Second, CZ in cheap settings is often glued or set in open-backed cups where lotion, soap and skin oil collect behind the stone. A good cleaning helps the grime part, but it cannot undo scratches.

Moissanite does not cloud in that way. Its surface stays hard, so a soak in warm water with mild soap and a soft brush brings it back. That is the same cleaning GIA recommends for diamond.

Time worn daily	Typical CZ	Typical moissanite
First months	Bright, very sparkly	Bright, strong rainbow fire
One to two years	Edges softening, small scratches on top	No visible change
Several years	Dull, glassy, often replaced	Light wear on sharpest edges at most

These are general wear patterns that follow from the hardness numbers, not test results for any one brand.

CZ costs very little per stone, which is why a full iced CZ chain can sell for less than a plain gold chain. Moissanite costs more per stone because it is harder to grow and cut, but still a small fraction of diamond. Real diamond, even lab-grown, is priced on the 4Cs and total carat weight.

For perspective, here are real diamond iced pieces from our showroom catalog, all solid gold:

Piece	Diamonds	Price
Mixed Lab Diamond Necklace 6.75 ct, 14K White Gold	6.75 ct lab	$5,500
Round Lab Diamond Necklace 18.48 ct, 14K Yellow Gold	18.48 ct lab	$6,500
Round Lab Diamond Necklace 30 ct, 14K White Gold	30 ct lab	$8,950
Round Lab Diamond Necklace 21.35 ct, 14K White Gold	21.35 ct lab	$7,300

Look at the price per carat in that table: the 30 ct necklace works out to roughly $300 per carat of lab diamond, gold included, because it is made of many small stones. Small diamonds are far cheaper per carat than one big stone, which is why iced diamond pieces are more reachable than people expect. A CZ or moissanite chain with a similar look will still be cheaper. The difference you pay for is a stone that is diamond and gold that is solid all the way through.

CZ is the easiest simulant to catch. It is a poor heat conductor, so a basic thermal diamond tester reads it as "not diamond" in a second. It is also heavy: a CZ the same size as a 1 carat round diamond weighs about 1.6 to 1.7 carats, so a loose CZ sitting on a scale gives itself away.

Moissanite moves heat almost as well as diamond, so it usually passes a thermal tester. That is where the "passes the diamond tester" sales line comes from. A multi-tester with an electrical check, or a loupe showing doubled facet edges, catches it. See how to spot fake diamonds and what moissanite is.

Care step	Cubic zirconia	Moissanite
Weekly clean	Warm water, mild soap, soft brush	Warm water, mild soap, soft brush
Ultrasonic cleaner	Risky if glued or in plated metal	Fine if the stones are set in solid metal
Store separately	Yes, other jewelry scratches it	Yes, it can scratch softer stones and metal
Remove for gym and pool	Yes, chlorine and knocks speed up wear	Recommended, mainly to protect the setting

The weak point of most simulant jewelry is not the stone but the setting. Glue lets go, plating rubs off, and thin prongs bend. If a piece has dozens of stones, check it under light every few weeks for empty seats. The same habit protects real diamond pieces, covered in how to spot fake diamonds and our cleaning guides.

• CZ: fast-fashion iced chains and pendants, low-cost watch bezel kits, costume rings, sample and display pieces.
• Moissanite: budget engagement rings, "VVS moissanite" tennis chains, studs, and iced pendants sold online.
• Diamond: fine jewelry from jewelers who disclose origin, grade and metal in writing.

Watch the metal as closely as the stone. A lot of CZ and moissanite jewelry is plated brass, stainless steel or sterling silver. Read how to tell if gold is real and how to tell if a Cuban link is real before paying gold prices.

Under the FTC Jewelry Guides, sellers must not call a simulant a diamond, and lab-made stones have to be described accurately. A listing that says "ice," "VVS" or "passes tester" without naming the stone is a red flag.

Simulant jewelry is sold with a vocabulary built to sound like diamond. Here is what common phrases usually mean on a listing:

Phrase on the listing	What it usually means
"Lab diamond simulant" or "lab created stone"	CZ or moissanite, not diamond
"VVS stones"	A clarity word borrowed from diamond grading, often used on moissanite
"Passes the diamond tester"	Moissanite on a thermal pen; CZ never passes
"Iced out" with no stone named	Usually CZ
"Gold" with no karat	Usually plated metal
"18K plated" or "GP"	A thin gold layer over brass or steel

A real diamond listing names the stone origin (lab-grown or natural), gives a carat weight, and states the gold karat. Our showroom iced necklaces, for example, are titled like "Round Lab Diamond Necklace 18.48 ct, 14K Yellow Gold," which tells you the stone, the weight and the metal in one line.

CZ can be made in almost any color by adding trace elements, so pink, blue, yellow and black CZ are cheap and common in fashion jewelry. Moissanite is sold mostly colorless, with a smaller range of colored stones that tend to look darker and less saturated than colored CZ. Neither tells you anything about a colored diamond, which is priced on its own scale.

Black stones are a special case. Black CZ and black moissanite both show up on iced men's rings and pendants. Black moissanite keeps its polish far longer, while black CZ shows scratches quickly because the dark surface makes every mark obvious. If you want color with real gems, sapphire and ruby are the next step up in hardness and value; our catalog has pieces like the Ruby Rose Earrings at $2,020, set with diamonds in gold.

Your situation	Best pick
Costume or one-night look, lowest price	CZ
Daily wear simulant that stays bright	Moissanite
Engagement ring or heirloom	Diamond, lab-grown or natural
Iced chain you will wear for years	Diamond set in solid gold

Between the two simulants, moissanite wins on every durability point. Between moissanite and diamond, read moissanite vs diamond, then are lab diamonds real and the iced out jewelry buying guide.