What Do You Call Fake Diamonds? Simulants and Their Names

In the jewelry trade, fake diamonds are called simulants, or simulated diamonds. The term covers any material that looks like a diamond but does not share its chemical composition, crystal structure, or optical properties. Cubic zirconia and moissanite are the two names shoppers hear most often, since both are lab-created stones sold specifically as diamond substitutes. Natural stones such as white sapphire, white topaz, and zircon also serve as simulants, though less often today. None of these should be confused with a lab-grown diamond, which is chemically identical to a mined diamond and goes by its own name.

What Do You Call a Fake Diamond

A fake diamond is called a diamond simulant, or simulated diamond, and jewelers sometimes shorten this to just a simulant. The Gemological Institute of America defines the term as a material that looks like another gem and works as its substitute but has very different chemical composition, crystal structure, and optical and physical properties. Shoppers also hear the phrases imitation diamond and diamond substitute, and all three terms point to the same idea: a stone that mimics a diamond’s look without matching what a diamond actually is.

The simulant category is broad. It includes stones grown in a laboratory purely to resemble diamonds, plus a handful of natural gems that happen to sparkle in a similar way. What unites them is a lower price than a mined diamond and a set of properties, hardness, refractive index, and durability among them, that a trained eye or a simple gem tester can tell apart from a genuine diamond.

What Are the Most Common Diamond Simulants

Cubic zirconia and moissanite are the two most common alternatives sold today, though several other lab-made and natural stones fill the same role. Amazon offers diamond simulants, including cubic zirconia, moissanite, and other alternatives, for comparison online.

Lab-Created Simulants

Zirconium dioxide is the base material for cubic zirconia, often shortened to CZ. Commercial production began in 1976, and the stone quickly became the most popular diamond simulant on the market because it is inexpensive and easy to cut into bright, symmetrical stones.

Moissanite is also lab-created today, even though the mineral was first discovered naturally inside a meteor crater. It reached consumers as a diamond alternative in 1998 and has since become the main rival to cubic zirconia. Older simulants still turn up in vintage jewelry, including yttrium aluminum garnet, gadolinium gallium garnet, synthetic rutile, and strontium titanate.

Synthetic rutile and strontium titanate were both popular between 1955 and 1970 for their intense fire, though strontium titanate is fragile. Flint glass, often cut into rhinestones, has been used as a diamond stand-in since the 1700s and remains the softest, most easily scratched option on this list.

Natural Gemstone Simulants

White sapphire is a natural stone, though lab-made versions exist too, and it offers solid resilience even if it cannot match a diamond’s scintillation. Topaz, particularly the white or colorless variety, sparkles nicely but is not ideal for daily wear, since its facets dull and can chip over time.

Zircon is a naturally occurring gem that has served as a diamond simulant for centuries and was historically known as the Matara diamond. Quartz, rock crystal, and the goshenite variety of beryl round out the list of natural simulants, alongside less common options such as white spinel, demantoid garnet, and tsavorite garnet.

How Do Diamond Simulants Differ from Lab-Grown Diamonds

These materials only look like diamonds, while lab-grown diamonds are chemically real diamonds grown under controlled conditions. A simulated stone lacks a diamond’s crystal structure and optical performance, but a lab-grown diamond shares every physical and chemical property a mined diamond has.

A simple memory aid keeps the two straight: simulated sounds like similar, since a simulant merely resembles a diamond, while synthetic sounds like authentic, since a synthetic diamond is the real thing made in a lab instead of the ground. Buyers who want an affordable stone that still counts as an actual diamond should look for lab-grown diamonds, not simulants. Those who want the diamond look at a lower price and do not mind a different set of properties are the ones simulants are built for.

How Durable Are Cubic Zirconia and Moissanite

Moissanite is significantly more durable than cubic zirconia, and the two stones age very differently after a few years on a hand worn daily.

Cubic Zirconia Durability and Lifespan

Cubic zirconia rates 8.0 to 8.5 on the Mohs hardness scale, compared with a diamond’s 10. That gap matters in daily wear, because CZ is prone to scratching and marring. The material is also somewhat porous, so it absorbs oils and chemicals from lotion, soap, and skin over time.

Most cubic zirconia stones last about two to three years under regular wear before they turn cloudy or milky, and that clarity cannot be restored by cleaning. As scratches build up, the stone loses brilliance, which is why some jewelers describe CZ as disposable jewelry rather than a long-term investment.

Moissanite Durability and Lifespan

Moissanite rates 9.25 to 9.5 on the Mohs scale, harder than sapphire’s 9.0 and just behind a diamond’s 10. It is non-porous, so it resists the daily scratches that dull cubic zirconia, and it does not cloud with age. Moissanite keeps its clarity and sparkle for decades, which makes it a realistic choice for an engagement ring or any piece meant for everyday wear rather than special occasions only.

How Do Simulants Compare on Price and Sparkle

Cubic zirconia is the cheapest diamond simulant by far, while moissanite costs more but throws more fire and light than any other substitute stone.

As of September 2026, cubic zirconia runs from about $20 to $50 per carat, with some retailers pricing loose stones under $10 per carat. Moissanite costs considerably more, typically $25 to $500 per carat depending on size and quality, with premium stones reaching $400 to $600 per carat. For comparison, a natural mined diamond runs anywhere from roughly $2,000 to $20,000 or more per carat, which is exactly why simulants exist in the first place.

A one-carat center stone illustrates the price gap well. Cubic zirconia that size typically costs under $50. A comparable moissanite stone runs somewhere between $400 and $600.

Natural diamonds of similar clarity and cut start around $2,000 and can climb past $20,000 depending on color, clarity, and cut grade. Shoppers comparing carat weight alone should keep that spread in mind before judging stone types by sticker price.

Optical performance explains part of the price gap too. Cubic zirconia has a refractive index of 2.15, which produces plenty of sparkle when a stone is new but looks increasingly glassy and dull as scratches accumulate. Moissanite has a much higher refractive index, 2.65 to 2.69, plus a dispersion rating of 0.104 that lets it split light into flashes of color.

It also shows birefringence, a doubling effect that can throw off rainbow-colored fire, and some gemologists say its brilliance actually surpasses a diamond’s under strong light. A diamond’s own refractive index sits around 2.42, between the two simulants, which is part of why moissanite can look even more sparkly than the stone it imitates.

The table below compares the four stones on hardness, brilliance, and cost.

Feature	Cubic Zirconia	Moissanite	White Sapphire	Diamond
Mohs Hardness	8.0 to 8.5	9.25 to 9.5	9.0	10
Refractive Index	2.15	2.65 to 2.69	about 1.76	about 2.42
Lifespan With Regular Wear	2 to 3 years	Decades or a lifetime	Decades or more	A lifetime
Clouds Over Time	Yes, becomes milky	No	No	No
Price Per Carat	$20 to $50	$400 to $600	Varies	$2,000 to $20,000 or more
Suitable for Daily Wear	No	Yes	Moderate	Yes

Which Diamond Simulant Is Better for an Engagement Ring

Moissanite is the better choice for an engagement ring meant for daily wear, while cubic zirconia suits occasional or budget jewelry instead.

An engagement ring gets knocked around every day, through dishwashing, gym workouts, and general life, so hardness and porosity matter more than sticker price. Moissanite’s 9.25 to 9.5 Mohs rating and non-porous surface mean it can handle that kind of wear for decades without clouding, while cubic zirconia’s softer, porous surface typically clouds within two to three years under the same conditions.

The price difference between the two, roughly $400 to $600 per carat for moissanite against $20 to $50 per carat for cubic zirconia, reflects that durability gap rather than any difference in how the stones look when new.

Cubic zirconia still makes sense for costume jewelry, a backup travel ring, or pieces a buyer expects to replace every few years anyway. Anyone set on a lifetime piece that will not need replacing should budget for moissanite, a lab-grown diamond, or a natural diamond instead, depending on how important it is that the stone be an actual diamond rather than a substitute.

“Up to” figures with no typical figure are a small irritation of mine, probably because they let a number look useful while doing very little work. Here, the more helpful check is the stated $400 to $600 per carat for moissanite against $20 to $50 for CZ: for a daily engagement ring, I would pay the gap for durability rather than gamble on a stone expected to last only two to three years.

How Can a Jeweler Tell a Simulant from a Real Diamond

A trained gemologist can identify a diamond simulant through visual inspection and specialized testing, mainly by checking optical properties a diamond cannot fake.

Refractive index and dispersion readings are the main tools, since every simulant material bends and splits light differently than a diamond does. A gemologist can also spot certain visual clues without equipment, moissanite’s doubling of facet edges under magnification, for example, or the cloudy, worn look that older cubic zirconia develops.

Paperwork offers another shortcut: the Gemological Institute of America does not issue grading reports for simulants at all, only for verified natural diamonds, so a stone sold without any report, or with a report from an unfamiliar lab, is worth extra scrutiny.

Buyers without gemological training have fewer options, but a jeweler with a loupe and a refractometer can usually settle the question in a few minutes. Anyone unsure whether a family stone or a bargain ring is a genuine diamond should bring it to an independent appraiser rather than relying on the seller’s word alone. The Gemological Institute of America’s simulant guide is a reasonable starting point for checking what a report does and does not cover.

Frequently Asked Questions

Can Cubic Zirconia Turn Yellow or Cloudy over Time?

Yes. Cubic zirconia is somewhat porous, so it absorbs oils and chemicals from everyday skin contact and cleaning products. Most CZ stones develop a cloudy or milky look within two to three years of regular wear, and that haze cannot be cleaned away once it sets in. Moissanite and diamond do not share this problem, since both are non-porous.

Is Moissanite Cheaper than a Real Diamond?

Moissanite costs far less than a diamond, and the gap is substantial. It typically runs $25 to $600 per carat depending on size and quality, while a natural mined diamond of similar size can run from about $2,000 to $20,000 or more per carat. Moissanite still costs more than cubic zirconia, but both remain far less expensive than a genuine diamond.

What Was Zircon Called Historically?

Zircon was historically known as the Matara diamond, a name tied to the region in Sri Lanka where much of the stone was mined. It has been used as a diamond simulant for centuries, long before cubic zirconia or moissanite existed. Zircon is a distinct mineral from cubic zirconia, despite the similar-sounding name.

Does the GIA Grade These Stones?

No. The Gemological Institute of America issues grading reports only for verified natural diamonds, not for simulants such as cubic zirconia or moissanite. A seller who offers a GIA report for a simulant stone is misrepresenting what that report covers. Buyers should confirm exactly what any report certifies before trusting it as proof of a genuine diamond.

Knowing the right vocabulary makes stone shopping far less confusing. These alternatives cover everything from bargain cubic zirconia to durable moissanite to old-fashioned rhinestones, and none of them are lab-grown diamonds despite looking similar in a ring setting. Matching the stone to how it will actually be worn, whether that means years of daily use or an occasional special event, matters more than the label on the price tag. Reading the receipt or asking the seller directly before checkout avoids confusion months or years down the road.

References

• Guide to Fake Diamonds: Materials & Names, Gema&Co
• What is a Simulated Diamond?, Luxuria Diamonds
• What are fake diamonds called? Simulated Diamonds vs Synthetic, Goodmans Jewelers
• What Are Simulated Diamonds?, Gemological Institute of America (GIA)
• More Info About Diamond Simulants, Gemological Institute of America (GIA)
• Diamond Simulant, Wikipedia
• Moissanite vs Cubic Zirconia: What’s The Real Difference?, Promise Moissanite

Sources read in September 2026.