The short answer

Natural and lab-grown diamonds are both diamond: the same carbon crystal, with essentially the same chemical, physical and optical properties. One formed in the earth; the other was grown in a laboratory. Cubic zirconia (CZ) and moissanite are different materials that look like diamond. Gemologists call them simulants. GIA describes the moissanite used in jewelry as synthetic, meaning it is made in a laboratory, but that does not make it a lab-grown diamond.

So when you compare listings that all look like diamonds, read the word that comes immediately before “diamond” or before the gem’s name. That word tells you which of the four you are buying, and it is where the FTC’s guidance expects the disclosure to sit.

Stone	What it is	Where it comes from	Hardness (Mohs)	What the label should say
Natural diamond	Diamond	Mined	10 (FTC definition)	“Diamond”; “natural” is reserved for stones that are not manufactured
Lab-grown diamond	Diamond, with the same properties as natural	Grown in a laboratory	10 (FTC definition)	“Laboratory-grown”, “laboratory-created” or similar, immediately before “diamond”
Cubic zirconia (CZ)	A different material that imitates diamond (a simulant)	Manufactured	8.5 (GIA)	Its own name; if “diamond” appears, “simulated” or “imitation” in front of it
Moissanite	Silicon carbide, another simulant	Made in a laboratory for jewelry	9.25 (GIA)	Its own name; if “diamond” appears, “simulated” or “imitation” in front of it, never “lab-grown” or “synthetic”

The rules quoted below come from the FTC’s Guides for the Jewelry, Precious Metals, and Pewter Industries (16 CFR Part 23), last revised in 2018. They set out what the FTC considers unfair or deceptive; this article explains them and is not legal advice. The CZ and moissanite hardness figures are from GIA, the Gemological Institute of America.

Two families: diamonds and simulants

The FTC Guides define a diamond in 16 CFR 23.12(a): “A diamond is a mineral consisting essentially of pure carbon crystallized in the isometric system. It is found in many colors. Its hardness is 10; its specific gravity is approximately 3.52; and it has a refractive index of 2.42.” A lab-grown diamond meets that definition. GIA puts it plainly: “Lab-grown diamonds have the same chemical, physical and optical properties as natural diamonds, while simulants do not.” Our guide to natural vs lab-grown diamonds covers how the two are grown, identified and priced.

Simulants are a different family: GIA says they “may look like diamonds, but they don’t have the same chemical, physical and optical properties”. In GIA’s words, “The most common diamond simulant that is a synthetic gemstone is synthetic cubic zirconia (CZ).” CZ is rated 8.5 on the Mohs scale and, GIA notes, “scratches more easily than diamond”. GIA also writes that if CZ is colorless, “its color has been shown to yellow over time and it can be somewhat brittle.”

“Synthetic moissanite, also known as silicon carbide (SiC), is another popular diamond simulant,” according to GIA, which lists it at 9.25 on the Mohs scale. Both are legitimate stones when they are named for what they are. They cost and wear differently from diamond, so you need the name to compare like with like.

Reading the word before “diamond”

“Diamond” on its own. Under 23.12(b), it is unfair or deceptive to use “the unqualified word “diamond” to describe or identify any object or product not meeting the requirements specified in the definition of diamond provided above”.
“Lab-grown”, “laboratory-created” or “[maker]-created”. These say the stone was made, not mined. 16 CFR 23.25(b) says a gem name used for a laboratory-made, imitation or simulated stone should be “immediately preceded with equal conspicuousness by the word “laboratory-grown,” “laboratory-created,” “[manufacturer name]-created,” or some other word or phrase of like meaning, or by the word “imitation” or “simulated,” so as to disclose clearly the nature of the product and the fact it is not a mined gemstone.” The diamond section of the Guides points to 23.25 for laboratory-created diamonds.
“Cultured”. For diamonds, 23.12(c)(3) accepts “cultured” only “if the term is qualified by a clear and conspicuous disclosure (for example, the words “laboratory-created,” “laboratory-grown,” “[manufacturer name]-created,” or some other word or phrase of like meaning) conveying that the product is not a mined stone.” “Cultured” alone does not tell you the stone was made in a laboratory.
“Synthetic”. Under 23.25(c), “It is unfair or deceptive to use the word “laboratory-grown,” “laboratory-created,” “[manufacturer name]-created,” “synthetic,” or other word or phrase of like meaning with the name of any natural stone to describe any industry product unless such product has essentially the same optical, physical, and chemical properties as the stone named.” A lab-grown diamond has those properties; a simulant, by GIA’s description, does not.
“Simulated” or “imitation”. These mean the stone only looks like the one named. A “simulated diamond” is not a diamond.
“Faux”. A note to 23.25(b) reads: “The use of the word “faux” to describe a laboratory-created or imitation stone is not an adequate disclosure that the stone is not a mined stone.”
“Natural”, “genuine” or “real”. 16 CFR 23.27: “It is unfair or deceptive to use the word “real,” “genuine,” “natural,” “precious,” “semi-precious,” or similar terms to describe any industry product that is manufactured or produced artificially.”

You will also meet “synthetic diamond” in older writing, including some of GIA’s articles, used for a lab-grown diamond.

Phrases that should make you look twice

Two stone names at once, such as “moissanite diamond”. If a listing combines them, ask which one it is.
“Synthetic diamond” used for a simulant. JCK reported in 2014 that “many consumers confuse ‘diamond simulants’ with ‘synthetic diamonds.'” The article also quotes a lab-grown diamond producer’s FTC submission claiming that moissanite and cubic zirconia “are frequently advertised as ‘synthetic diamonds.'” That is the producer’s claim, not an FTC finding.
A disclosure placed somewhere else. In 2019 FTC staff sent eight warning letters to jewelry marketers about diamond ads, pointing to ads that “might imply that a simulated diamond is a lab-created or mined diamond” and to disclosures that “are not proximate to the individual product descriptions.” The FTC’s consumer alert that day described information about how a stone was made sitting on a “diamond education” webpage instead of near the ad. Look for the origin word in the title or right beside it.

The same rule applies to colored gems

The Guides allow “lab-grown” or “synthetic” with a stone’s name only when the product has “essentially the same optical, physical, and chemical properties as the stone named” (23.25(c)), so a correctly labelled lab-grown sapphire is sapphire made in a laboratory, in the same way a lab-grown diamond is diamond. Under 23.25(a) and (b), a gem’s unqualified name is for “a mined stone of the type described”; a stone that was made needs “laboratory-grown” or a similar word immediately before the name.

Our 14K Yellow Gold 9×7 mm Lab-Grown Blue Sapphire Bezel-Set Charm/Pendant shows the pattern: “Lab-Grown” sits directly before “Blue Sapphire” in the title, and the listing’s stone disclosure describes it as “created in a laboratory; same chemistry as the natural stone”. A “simulated sapphire” would be a different material that only looks like sapphire.

Can you tell them apart by looking?

Usually not with any confidence. GIA says simulants “are easily identifiable by their optical and physical characteristics”, but in practice checking those characteristics is a job for a trained gemologist with instruments, not a glance at a ring on your hand. In 2015 JCK relayed a local TV report about a jeweler who was said to have sold a pair of moissanite earrings as diamonds; according to the report, the buyer learned they were synthetic moissanite only when he had them appraised.

If identity matters to you, rely on a clear written description from the seller and, for a stone you already own, an independent gemologist. A grading report from a laboratory describes one individual stone. Finished jewelry with set stones from IMPERVORA ships without an individual grading report unless the product page says otherwise, so ask before you order if you need one.

How IMPERVORA names its stones

Our Lab-Grown Diamonds and Natural Diamonds categories group pieces by origin, and almost every title in them includes “Lab-Grown” or “Natural”; a few pieces offered with a choice of gemstones or diamonds show the stone type in their options instead. Many of our other diamond pieces, including most diamond wedding bands, are listed in the broader Diamonds category with “Diamond” in the title and no origin word. If origin matters to you, email Concierge@impervora.com before you order and we will tell you what the supplier records for that piece. Our guide to choosing a diamond covers the 4Cs once you know which kind you want.

Where we sell cubic zirconia, the title says so. The 14K White Gold 2 mm Round Cubic Zirconia Stud Earrings, Four-Prong Set with Push Backs name the stone in the title, and the product details list the stone as cubic zirconia, with a stone creation method of “Simulated” and a treatment method of “Not Treated”. We do not sell moissanite; it is explained here only so you can read other labels. Both products linked above were available to order at the time of writing.

IMPERVORA sells the pieces linked above, chosen as examples of how stones are named on a label.

Next step

When you compare listings, read the word directly in front of “diamond” or the gem’s name before you look at the price. If that word is missing, unclear or only explained on another page, ask the seller to confirm in writing what the stone is.