Moissanite is silicon carbide, a diamond simulant, and under the Federal Trade Commission’s Jewelry Guides at 16 CFR 23.12 the unqualified word “diamond” may not be used to describe it. A diamond is a different material: a mineral consisting essentially of pure carbon crystallized in the isometric system, with a hardness of 10.
That settles the moissanite vs diamond question at the level of the label. What is left for a buyer is four differences: how each stone handles light, a hardness of 9.25 against 10, what each one costs, and the words a seller is required to put on the tag. This guide works through all four from what the FTC and GIA publish, including the one number nobody publishes at all.
Key Takeaways
- Moissanite is silicon carbide with a Mohs hardness of 9.25, against diamond’s 10, and GIA calls it one of the hardest gemstones available, second only to diamond.
- The FTC defines a diamond as essentially pure carbon crystallized in the isometric system, hardness 10, specific gravity about 3.52 and refractive index 2.42, and calls it unfair or deceptive to use the unqualified word “diamond” for anything that does not meet that definition (16 CFR 23.12).
- Under 16 CFR 23.25(b), a simulated or laboratory-created stone must carry a qualifier such as “imitation” or “simulated” immediately before the gem name, with equal conspicuousness; a Note says “faux” is not an adequate disclosure.
- Moissanite is doubly refractive, so a viewer sees a double image of its back facets, and GIA says that in very large sizes its display of extreme fire is sometimes called the “disco ball” effect.
- GIA says moissanite costs much less than comparable diamonds, but no authority publishes a moissanite price, so any figure you find is one seller’s listing on one day.
Is Moissanite a Diamond?
No. Moissanite is a diamond simulant, a different mineral, and United States marketing guidance treats the two as different products with different required labeling. The question persists because the resemblance is convincing: GIA writes that while simulants “may flash and dazzle like a diamond, it is important to know that they are not diamonds,” and that they are “completely unrelated to diamonds at the atomic level.”
What Moissanite Is Made Of
Moissanite is silicon carbide, written SiC, a compound of silicon and carbon rather than carbon alone. GIA groups it with cubic zirconia and glass as the common diamond simulants, “easily identifiable by their optical and physical characteristics,” and gives it a hardness of 9.25 on the Mohs scale. Read that figure for what it is: a published Mohs value describes the pure material in a laboratory, not a finished ring.
How the FTC Defines a Diamond
The FTC’s definition is a materials test, not a marketing opinion. Section 23.12 reads: “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.”
The operative half comes next. The same section calls it “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.” Silicon carbide does not meet them. Note what the Jewelry Guides are not: not a statute, not a court ruling, not a product ban. They govern what a stone may be called, not whether it may be sold.
What a Seller Is Required to Disclose
Under 16 CFR 23.25(b), words such as “stone,” “gem,” “gemstone” or the name of a precious or semi-precious stone may be used for a laboratory-grown, synthetic, imitation or simulated stone only when that word is “immediately preceded with equal conspicuousness” by “laboratory-grown,” “laboratory-created,” “[manufacturer name]-created,” or by “imitation” or “simulated.”
Two details do the work: the qualifier has to be adjacent, not buried in a specification table further down, and equally conspicuous, so a large gem name over a small footnote does not satisfy it. A Note closes one loophole by name: “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.” For a buyer that means reading the tag and the receipt rather than the headline.
Moissanite vs Lab Grown Diamond, in Short
A lab grown diamond is a diamond; moissanite is not, and that is the entire difference. The FTC removed the word “natural” from its definition in 2018, reasoning that lab-created products with essentially the same optical, physical and chemical properties as mined diamonds are also diamonds (Federal Register, 2018). If that is the comparison you want, see lab grown and natural diamonds compared.
Moissanite vs Diamond, Side by Side
Here is what the FTC Jewelry Guides and GIA say about each stone on the points that matter at a counter.
| Moissanite | Diamond | Source | |
|---|---|---|---|
| Material | Silicon carbide (SiC), unrelated to diamond at the atomic level | Essentially pure carbon crystallized in the isometric system | GIA; FTC 16 CFR 23.12 |
| Mohs hardness | 9.25 | 10 | GIA; FTC 16 CFR 23.12 |
| Refraction | Doubly refractive: a viewer sees a double image of the back facets | Singly refractive, refractive index 2.42 | GIA; FTC 16 CFR 23.12 |
| What it may be called at the point of sale | Moissanite, or a “simulated” or “imitation” stone with that word immediately adjacent and equally conspicuous; “faux” is not enough | Diamond, once it meets the definition; “laboratory-grown” or “laboratory-created” when it was grown | FTC 16 CFR 23.25(b) and Note 1; 16 CFR 23.12(c)(3) |
| What a screening device says | Some consumer devices may pass a simulant as natural; the GIA iD100 is built to separate simulants and returns Pass or Refer | ”Pass” indicates natural; “Refer” means further laboratory testing | GIA, Gems & Gemology (2024); GIA iD100 |
| Published market figures | None: no authoritative source publishes a moissanite price | Natural rings averaged $7,000 at 1.6 carats and lab-grown $4,300 at 2 carats for couples married in 2025 | Rapaport News reporting The Knot (2026) |
Composition and Hardness
Moissanite sits at 9.25 on the Mohs scale and diamond at 10, and the gap is wider than it looks, because Mohs ranks what scratches what rather than setting equal steps. GIA still places moissanite second only to diamond among gemstones. On moissanite vs diamond strength in daily wear, both sit above the grit in household dust, and in both cases the figure describes the pure material rather than the far softer gold or platinum holding it.
How Each One Handles Light
The visible difference is not how bright the two are but what kind of flash they throw. GIA describes synthetic moissanite as having brilliance “only slightly less than a natural diamond,” which is why moissanite vs diamond shine is rarely settled by brightness in a store window. What separates them is double refraction, covered next.
What Comes With the Stone on Paper
A diamond can come with a grading report from a gem laboratory that identifies and grades it, while a moissanite typically arrives with a manufacturer’s warranty or certificate instead. That is a difference in the kind of document, not a judgment about the stone. We publish no grading tiers for moissanite, because no gemological authority we read publishes one.
Double Refraction: Why Moissanite Sparkles Differently
Moissanite is doubly refractive and diamond is not, which is the physical fact behind almost everything buyers report seeing. GIA states it plainly: moissanite “is also different from diamond visually in that it is doubly refractive, so viewers will see a double image of its back facets.” That doubling is both the source of the rainbow fire and the most reliable way to spot the stone by eye.
What Doubly Refractive Means
In a doubly refractive material a single ray entering the stone splits into two, which travel at slightly different speeds and emerge along slightly different paths. Look down through the crown at an angle and the crisp edges of the back facets appear as two lines instead of one, slightly offset. Diamond is singly refractive, with the refractive index of 2.42 written into the FTC definition, so those edges stay single.
The Disco Ball Effect at Larger Sizes
GIA writes that in very large sizes, moissanite’s “display of extreme fire is sometimes called the ‘disco ball’ effect.” That is GIA’s own phrasing, and it reads better as a description than a verdict: plenty of buyers choose the stone for exactly that quality, while others read it as costume at size. GIA gives no carat threshold, so there is no number to shop by. Look at a large stone in room light rather than under a display spotlight.
The Color Cast Some Stones Show
GIA notes that “some moissanites look slightly yellow or gray when viewed at certain angles,” and its buyers guide describes synthetic moissanite as sometimes carrying a slightly greenish or grayish hue. This varies stone to stone and is not tied to any brand or product line. View a stone in daylight, off the seller’s lighting, and tilt it through a full range of angles first.
How to Tell a Moissanite From a Diamond
The reliable tells are optical and laboratory-based, not the tricks that circulate online. Most of what passes for a moissanite vs diamond test on social media proves nothing about the material, and one of them, dragging a stone across a surface to see what scratches, damages the stone being tested.
Look for Doubled Facet Edges Under a Loupe
Tilt the stone and look down through the crown with a loupe, watching the back facet edges for the doubling that a singly refractive diamond cannot show. It is not foolproof in the hand: a mounted stone limits your angles, and a cutter can orient the rough so the doubling is least visible face up. Seeing it is strong evidence; not seeing it proves nothing.
Why a Handheld Tester Can Be Wrong
A handheld tester gives a screening result, not an identification. GIA’s 2024 Gems & Gemology research explains that most consumer screening tools return a “pass” or “refer” result, with “pass” indicating the sample is natural, and warns that “some screening devices may not be able to refer simulants, incorrectly passing them as natural.” GIA describes its own iD100 as distinguishing natural diamonds from laboratory-grown diamonds and diamond simulants, returning Pass or Refer, and testing mounted and loose stones of 0.9 mm or greater in diameter.
What the Paperwork Tells You
The document that settles the material is a report from a gem laboratory naming what the stone is; a warranty card says who stands behind the purchase, which is not the same thing. Before money changes hands, ask for the stone’s identity stated on the invoice, then check that wording against the disclosure language above.
Durability and Everyday Wear
Both stones are hard enough for daily wear, and hardness is only half of what keeps a center stone intact. The other half, toughness, is where most ring damage actually happens.
9.25 vs 10, and What That Number Does Not Cover
Moissanite is 9.25 on the Mohs scale and diamond is 10, both far above the everyday abrasives a ring meets on a desk or a car door, so visible scratching is unlikely for either in normal wear. What the number does not cover is everything around the stone: not the alloy of the band, not the prongs or bezel, and not the small accent stones in the shoulders, all of which are softer and will show wear first.
Hardness Is Not Toughness
Hardness measures resistance to scratching; toughness measures resistance to breaking and chipping. GIA is blunt about diamond here: it is “very stable and extremely hard, but only somewhat tough,” with hardness uneven along different directions of the crystal. GIA also describes where the damage comes from: “Chips typically occur when the girdle (edge) or point of a diamond strikes something hard,” with countertops and rings worn next to each other among the common causes. No Mohs figure protects against that, for either stone.
Settings That Protect Either Stone
The setting does more for a center stone’s survival than the difference between 9.25 and 10 ever will. GIA’s advice is specific: vulnerable points or corners are better protected with bezels, partial bezels or V-shaped prongs. If your hands are busy all day a low profile helps too, which is the logic behind our guide to engagement rings for nurses; for how an enclosed rim works, see a bezel setting.
Cleaning and Care
Warm water, mild soap and a soft brush clean either stone at home, and GIA 4Cs recommends periodic professional cleaning alongside that. Ultrasonic machines need caution: GIA warns that the vibration “can sometimes shake gems loose or cause damage if gems are set with their girdles touching,” and that such cleaners can dislodge stones that are already loose, so stones should be checked before and after.
Price: What Each Costs and What Nobody Publishes
Diamond spending is documented by named, dated surveys, while no authoritative source publishes a moissanite price at all. That asymmetry is the honest frame for any moissanite vs diamond price comparison, and the reason this section names figures on one side and refuses to invent them on the other.
What Couples Actually Paid for Diamonds
Couples married in 2025 paid an average of $7,000 for a natural-diamond engagement ring at an average of 1.6 carats, and $4,300 for a lab-grown one at an average of 2 carats, as Rapaport News reported from The Knot’s study (2026). Those averages span a wide field: The Knot (2025) puts a one-carat natural diamond anywhere from $2,000 to $16,000 depending on its 4Cs. For budgets by stone and setting, see what couples spend on an engagement ring.
Where Moissanite Sits
GIA says moissanite “cost much less than comparable diamonds, allowing buyers to select larger stones or more intricate designs without exceeding their budget,” and that is as specific as any gemological authority gets. There is no per-carat table, no published index, no survey of what buyers paid. Every moissanite price online is one seller’s listing on one day, with no published reference to check it against, so compare two or three named sellers on the day you buy.
Value Later: The Honest Answer
No named, dated source publishes resale data for moissanite, so anyone quoting a resale percentage for it is guessing, and we would rather say so than fill the gap. What is documented is the market around it: The Knot Worldwide (2026) found that lab-grown center stones account for 61% of all engagement ring purchases, with an average spend of $4,600 among couples married in 2025. Buy either stone for how it looks and wears, and insure it rather than treating it as an investment.
Which Should You Choose?
The decision usually comes down to which of these things you care about most, with the source behind each one.
| If this is you | The better pick | Why | Source |
|---|---|---|---|
| You want a laboratory report identifying the exact stone | Diamond | Gem laboratories grade diamonds; a simulant comes with a seller’s or maker’s paperwork instead | GIA |
| You want the largest stone your budget allows | Moissanite | GIA says moissanite costs much less than comparable diamonds, allowing larger stones or more intricate designs within a budget | GIA, Diamond Alternatives: Engagement Rings |
| Rainbow flashes delight you | Moissanite | It is doubly refractive and shows extreme fire, called the “disco ball” effect in very large sizes | GIA |
| You want white flashes and a quieter sparkle | Diamond | Diamond is singly refractive, so the back facets do not double and the fire is less extreme | GIA |
| You work with your hands and knock the ring constantly | Either, in a protective setting | Hardness is not toughness: chips happen when a girdle or point strikes something hard, and bezels, partial bezels or V-shaped prongs protect vulnerable edges | GIA (2016) |
| You want the stone to hold a resale market | Diamond | Diamond spending and pricing are reported by named surveys; no named, dated source publishes moissanite resale data | Rapaport News reporting The Knot (2026) |
| You want a diamond, grown rather than mined | Lab-grown diamond, not moissanite | The FTC removed “natural” from its definition of diamond in 2018, so a lab-grown diamond is a diamond; moissanite is a different mineral | FTC, Federal Register (2018) |
When a Diamond Is the Better Buy
A diamond earns its price when the paperwork, the resale market or the tradition matters to the person who will wear it. An independent laboratory report identifying and grading your specific stone travels with the ring for insurance and appraisal. It is also the answer if you want the hardest known center stone, or one the trade prices openly enough to check a quote against published market data.
When Moissanite Is the Better Buy
Moissanite earns its place when size or design matters more than material, which is GIA’s own framing when it says the stone costs much less than comparable diamonds and lets buyers choose larger stones or more intricate designs. It is also the sensible pick for a ring that takes real abuse or travels, and for anyone who genuinely likes the rainbow flash rather than tolerating it. Shape affects how much of it you see, which our guide to engagement ring shapes covers in detail.
The Other Simulants: Cubic Zirconia and White Sapphire
Moissanite is not the only simulant, and the hardness gaps between them are real, which is the short answer to moissanite vs diamond vs cubic zirconia.
| Stone | Mohs hardness (GIA) | What GIA says |
|---|---|---|
| Moissanite | 9.25 | One of the hardest gemstones available, second only to diamond; doubly refractive |
| Colorless sapphire | 9 | Behind only diamond and moissanite in hardness, well suited to everyday wear |
| Cubic zirconia | 8 to 8.5 | Durable and suitable for everyday wear, but more prone to scratches and abrasions over time, and colorless CZ has been shown to yellow over time |
GIA describes cubic zirconia as made by heating powdered zirconium oxide to its melting point, and notes that its low cost, often less than 5% of a comparable diamond, keeps it accessible.
Frequently Asked Questions
Is Moissanite Better Than a Real Diamond?
Neither is better outright; they are different materials with different strengths. Moissanite gives you more size and more colored fire for a given budget, per GIA. A diamond gives you the hardest known gem material, an independent laboratory report on your exact stone, and an openly reported market price.
Is Moissanite Considered Fake?
It is a genuine gemstone, but it is classed as a diamond simulant rather than a diamond. GIA puts moissanite alongside cubic zirconia and glass in that category. “Fake” is the wrong word for a real mineral; the accurate words, and the ones FTC guidance expects on the tag, are “simulated” or “imitation” beside the gem name.
What Are the Downsides to Moissanite?
Three, all documented by GIA. Its hardness of 9.25 sits below diamond’s 10. Some stones read slightly yellow or gray at certain angles, or slightly greenish. And the extreme fire that GIA nicknames a disco ball effect in very large sizes reads as costume to some buyers, which is taste rather than quality.
Do Wealthy People Wear Moissanite?
No survey identifies who buys moissanite by income, so nobody can honestly answer that with data. What is documented is the appeal: GIA notes the stone lets buyers choose larger sizes or more intricate designs for a given budget, a reason that applies at any spending level rather than only at the lower end.
Can I Shower With My Moissanite Ring?
Water will not harm the stone, but the setting is the reason to take it off. Soap film builds up underneath and dulls the stone, and a wet, soapy ring slips off a finger easily. GIA 4Cs suggests periodic professional cleaning, and the prongs deserve a check by a jeweler once or twice a year.
What Looks Like a Diamond but Is Cheaper?
Moissanite, cubic zirconia and colorless sapphire are the usual answers, and GIA publishes a hardness figure for each: 9.25, 8 to 8.5, and 9 respectively. GIA notes that cubic zirconia often costs less than 5% of a comparable diamond, and that colorless CZ has been shown to yellow with time.
What Is a Poor Man’s Diamond Called?
The phrase usually means cubic zirconia, the cheapest of the common simulants, though moissanite also gets the label. GIA describes CZ as made by melting powdered zirconium oxide in a metal chamber. Both are simulants under GIA’s classification, and neither may be sold using the unqualified word diamond.
Sources
- Federal Trade Commission, eCFR, 16 CFR Part 23, Guides for the Jewelry, Precious Metals, and Pewter Industries, section 23.12, 2018, current as accessed 11/09/2026.
- Federal Trade Commission, eCFR, 16 CFR Part 23, section 23.12(c)(3), 2018, current as accessed 11/09/2026.
- Federal Trade Commission, eCFR, 16 CFR Part 23, section 23.25(b) and Note 1, 2018, current as accessed 11/09/2026.
- Federal Trade Commission, Federal Register, Guides for the Jewelry, Precious Metals, and Pewter Industries, 2018.
- GIA, An Introduction to Imitation Diamonds & Other Gems, undated, accessed 11/09/2026.
- GIA, Simulants, Moissanite and Lab-Grown Diamonds, undated, accessed 11/09/2026.
- GIA, Diamond Alternatives: Engagement Rings, undated, accessed 11/09/2026.
- GIA, Jewelry Buyers Guide to Diamond Alternatives, undated, accessed 11/09/2026.
- GIA (Al Gilbertson), How to Protect Your Diamond from Chipping, 2016.
- GIA 4Cs, Complete Guide to Engagement Ring Settings: Types vs. Styles, 2026.
- GIA 4Cs, Ultrasonic Cleaners for Gems: What You Need to Know, 2015.
- GIA, Gems & Gemology (Eaton-Magana, Hardman, Odake), Laboratory-Grown Diamonds: An Update on Identification and Products Evaluated at GIA, 2024.
- GIA, GIA iD100, undated, accessed 10/09/2026.
- Rapaport News, Lab-Grown ‘Taking Over’ Engagement-Ring Spending: The Knot, 2026.
- The Knot, Here’s The Average Engagement Ring Cost in 2025, According to Real Couples, 2025.
- The Knot Worldwide, The Knot Worldwide Unveils 2026 Real Wedding Study, 2026.