Moissanite is not a diamond, and a lab-grown diamond is. Moissanite is silicon carbide, a different mineral that is grown in a lab and cut to look like a diamond; a lab-grown diamond is carbon in the same crystal as a mined diamond, with the same hardness, the same sparkle and the same grading report. The practical differences are four: moissanite throws more rainbow fire, is a little softer (9.25 against 10 on the Mohs scale), weighs about 9% less at the same size, and costs a fraction of the price. On September 25, 2026 a 6.5 mm round moissanite, the size of a one-carat diamond, sold loose for $225 to $375 depending on the brand; a one-carat round lab-grown diamond in our picker started at $640. We sell lab-grown diamonds and not moissanite, so read this with that in mind, but the comparison below is meant to be the honest one: what each stone is, how each sparkles, wears and tests, what each really costs at the same size, and who should buy which.
Moissanite vs lab-grown diamond at a glance
| Moissanite | Lab-grown diamond | Mined diamond | |
|---|---|---|---|
| What it is | Silicon carbide, grown in a lab | Carbon in the diamond crystal, grown in a lab | Carbon in the diamond crystal, dug from the ground |
| Hardness (Mohs) | 9.25 | 10 | 10 |
| Refractive index | 2.65 to 2.69 | 2.42 | 2.42 |
| Fire (dispersion) | 0.104: strong rainbow flashes | 0.044: mostly white sparkle with some color | 0.044 |
| Weight at the same size | About 9% lighter; sold by diamond-equivalent weight | True carat weight | True carat weight |
| How light passes through it | Doubly refractive: facets look doubled under a loupe | Singly refractive: crisp facet edges | Singly refractive |
| Color | Maker's grades, colorless to faint tint; older stones look green-yellow | D to Z on an IGI or GIA report | D to Z |
| Diamond tester | Fools a heat tester; caught by an electrical or dual tester | Reads as diamond on every tester | Reads as diamond |
| Grading | Manufacturer's certificate or warranty | Independent lab report, laser-inscribed | Independent lab report |
| Loose stone, 6.5 mm round (a one-carat look) | $225 to $375 | From $640 | Several thousand dollars |
| Resale | Little | Little | A fraction of retail |
What moissanite is
Moissanite is silicon carbide, a crystal of silicon and carbon. The French chemist Henri Moissan found the first grains of it in 1893 in a meteorite crater in Arizona and mistook them for diamond; natural moissanite is so rare that every stone in a piece of jewelry is grown in a lab, which has been possible in gem sizes since the 1990s. For twenty years one company, Charles & Colvard, held the patents and sold every gem-grade stone; when the last of them expired in 2015, the price of moissanite fell hard and it became the stone of choice for people who want a big, bright, white gem for very little money. Modern moissanite is sold in maker's color grades, colorless (D to F), near-colorless (G to I) and faintly tinted, and the best of it looks very white; the older stones, and some cheap new ones, carry a green or yellow cast that shows in daylight.
What a lab-grown diamond is
A lab-grown diamond is a diamond. It is carbon arranged in the diamond crystal, grown in a chamber over weeks rather than in the earth over a billion years, and it has the same hardness, the same refractive index, the same fire and the same chemistry as a mined stone; a gemologist needs specialized equipment to tell them apart, and a diamond tester cannot. It is graded on the same scale by the same laboratories, IGI and GIA, and it carries its report number laser-inscribed on its girdle. Every stone in our picker is one. Our lab-grown diamond guide covers how they are grown and graded, and are lab-grown diamonds real answers the question in its title.
Is moissanite a lab-grown diamond?
No, and the confusion is understandable, because both are grown in a lab and both are sold as alternatives to mined diamonds. The word that separates them is simulant. A lab-grown diamond is a synthetic diamond: the same material as the natural stone, made a different way. Moissanite, like cubic zirconia, is a diamond simulant: a different material that is cut to look like a diamond. "Lab-grown moissanite" is a real phrase but a redundant one, since all moissanite is lab-grown, and "moissanite diamond" is a phrase to be wary of, because there is no such thing. If a listing does not say plainly whether the stone is a diamond or moissanite, ask; a reputable seller will say, and a lab report settles it.
Sparkle: fire against brilliance
This is where the two stones look different, and it is the difference that decides most people. Sparkle has two parts. Brilliance is white light returned to the eye; fire is white light split into colors, the way a prism does. Moissanite has a higher refractive index than diamond, 2.65 to 2.69 against 2.42, so it returns a little more light, and it has more than twice the dispersion, 0.104 against 0.044, so far more of that light comes back as color. In a small stone the effect is a livelier sparkle. In a large stone, or in direct sunlight, it becomes what people call the disco-ball effect: a scatter of rainbow flashes that a diamond does not make. Some people love it; to others, particularly people who know diamonds, it reads as glassy, and it is the single most reliable way to spot moissanite from across a room.
A diamond's sparkle is quieter and whiter. Its fire is there, but it is a smaller share of the light, and the facet edges stay crisp because a diamond is singly refractive: light passes through it as one ray. Moissanite is doubly refractive, light splits into two rays inside it, and under a jeweler's loupe the facets on the far side of the stone look doubled, a soft ghost image beside each edge. You cannot see that with the naked eye, but you can see what it does at a distance, which is a slightly softer, less defined sparkle in moissanite and a harder, more precise one in diamond. Neither is wrong; they are different, and the honest advice is to look at both in daylight before you decide.
Hardness and how each one wears
Diamond is a 10 on the Mohs scale, the hardest material there is, and nothing in daily life scratches it except another diamond. Moissanite is 9.25, harder than sapphire and ruby, which are 9, and hard enough for a ring worn every day for decades; the difference matters only at the margins, since a moissanite can be scratched by a diamond, which happens when rings are stored in a heap, and a diamond cannot. Both are tough enough for an engagement ring, both chip if struck hard on a thin edge, and both should come off for the gym, the garden and any work with tools. The claim that moissanite goes cloudy over time is half true: the stone itself does not change, but it holds skin oil and soap film more visibly than a diamond does, and an uncleaned moissanite looks dull in a way an uncleaned diamond also does, only sooner. A soft brush and warm soapy water restore either. Our page on how long lab-grown diamonds last has the long view: forever.
The weight trap: carats and diamond-equivalent weight
Moissanite is lighter than diamond, 3.21 against 3.52 in specific gravity, so a moissanite cut to exactly the size of a one-carat diamond weighs about 0.88 carats. The trade solves this by selling moissanite in "diamond-equivalent weight": a 6.5 mm round is called a one-carat moissanite because a one-carat diamond is about 6.5 mm across, even though it weighs less. That is fair as long as you know it, and it means the only sane way to compare the two is by millimeters, not carats. A one-carat round diamond is about 6.4 to 6.5 mm across; a two-carat is about 8.1 mm; a three-carat about 9.3 mm. Our picker lists every diamond's measurements next to its weight, and any moissanite seller worth buying from lists the millimeter size first.
Color, clarity and grading
A lab-grown diamond is graded by an independent laboratory on the same D-to-Z color scale and the same clarity scale as a mined diamond, and the report is tied to the stone by a laser inscription on the girdle. We stock D to G color and IF to VS2 clarity, which is the top of both scales, because the price of a lab-grown stone no longer punishes you for it. Moissanite has no independent grading; the maker assigns a color range and issues a certificate of authenticity or a warranty, and clarity is not graded at all, since the stones are grown clean. Colorless moissanite from a good maker is white; the older, cheaper and unbranded stones are where the green and yellow tints live, and they are the reason the stone got its reputation for looking artificial.
How to tell moissanite from a diamond
At home, three checks. Look for rainbow: tilt the stone under a lamp or in sunlight, and if the flashes are mostly colored rather than white, it is probably moissanite. Look through a 10x loupe at the facets on the far side of the stone through the table; doubled edges mean moissanite, crisp single edges mean diamond. Weigh it, if it is loose: a stone that measures like a one-carat diamond but weighs 0.88 carats is moissanite. At a counter, the tool matters. The common pen-style diamond tester measures heat conduction, and moissanite conducts heat almost as well as diamond, so a heat tester will call a moissanite a diamond; that is how moissanite ended up in rings sold as diamond. An electrical tester, or a dual tester, catches it, because moissanite conducts electricity and, with rare exceptions, diamond does not. And the report settles everything: a lab-grown diamond carries an IGI or GIA report and a matching inscription, which moissanite never has. Our guide to diamond testers and lab-grown diamonds explains what each tester reads.
Price: the real numbers, at the same size
Because the two are sold by different measures, the only honest comparison is loose stone against loose stone at the same millimeter size. Here are the prices we found on September 25, 2026: for moissanite, the published price list of a large online moissanite seller for its own colorless round stones and for Charles & Colvard's Forever One, the best-known brand; for lab-grown diamonds, the lowest price in our picker for D to G color, IF to VS2 clarity rounds of the matching carat weight.
| Round, size across | Diamond weight | Unbranded moissanite | Forever One moissanite | Lab-grown diamond, Clairamor picker |
|---|---|---|---|---|
| 6.5 mm | 1 ct | $225 | $375 | $640 |
| 7.5 mm | 1.5 ct | $275 | $600 | $923 |
| 8 mm | 2 ct | $300 | $750 | $1,178 |
| 9.5 mm | 3 ct | $425 | $1,200 | $1,890 |
Two things stand out. Moissanite is cheap, and unbranded moissanite is very cheap: a three-carat look for $425. And the gap to a lab-grown diamond, which was ten to one a few years ago, has closed to two or three to one, because lab-grown diamond prices have fallen so far. In a finished ring the gap shrinks again, since the setting costs the same whatever is in it. Charles & Colvard's oval solitaire with a two-carat-equivalent Forever One moissanite in 14k white gold was $1,549 on their site that day; our oval solitaire in 14k white gold with a two-carat lab-grown oval was $950 plus $1,193, which is $2,143. That is a real difference, $594, but it is the difference between two rings that will be worn for forty years, and it buys a diamond. With a one-carat oval ($719) our ring is $1,669. The pricing guide has the full picture of where lab-grown prices are.
Resale, insurance and the question of "real"
Neither stone should be bought as an investment. A lab-grown diamond resells for a fraction of its price, and so does a mined one; moissanite resells for almost nothing, because it costs almost nothing new. Both can be insured, and a lab-grown diamond comes with an appraisal that makes it simple. On the word "real": moissanite is a real gemstone and a real mineral, it is simply not a diamond, and the only dishonest thing about it is a seller who lets a buyer think otherwise. A lab-grown diamond is a real diamond, and the Federal Trade Commission's guidance treats it as one, with the word "lab-grown" as the required disclosure. The question to ask yourself is not which one is real but which one you want: a diamond, or a bright white stone that is not a diamond and costs less.
Who should buy moissanite, and who should buy a lab-grown diamond
Buy moissanite if the budget is the whole decision and a few hundred dollars is what there is; if you want a very large stone, three carats and up, at a price no diamond can meet; if you like the rainbow flash, and you should check that you do in sunlight before buying; or if the ring is a placeholder, a travel ring or a fashion piece rather than the one you will wear for life. Buy from a maker with a color grade and a warranty, compare by millimeters, and expect the stone to need cleaning more often.
Buy a lab-grown diamond if you want a diamond: the white sparkle, the crisp facets, the hardness that nothing scratches, a report from IGI or GIA with your stone's number on it, and a stone that passes every tester and every appraiser without a conversation. At today's prices that costs two to three times the moissanite at the same size, which for a one-carat round is $265 to $415 more for the stone, and it is what we sell, because when someone asks us whether their ring is a diamond, we want the answer to be yes without a footnote.
Where Clairamor fits
Every ring we make is set with a lab-grown diamond you choose from our picker, graded D to G and IF to VS2 by IGI or GIA, with the report number inscribed on the stone, so the setting price is the setting alone and the stone is added at the price you see. Every ring carries a lifetime warranty against manufacturing defects, comes with an appraisal for insurance, and includes one complimentary resize within 100 days for clients in the USA. We do not sell moissanite, and we will tell you plainly if a stone you bring us is one.
Lab-grown diamond engagement rings Solitaire settings Lab-grown diamonds explained
Not sure what you are looking at? Book a design consultation and bring the stone; we will put it under the loupe and the tester with you.
Frequently asked questions
Is moissanite a lab-grown diamond?
No. Both are grown in a lab, but moissanite is silicon carbide and a lab-grown diamond is carbon in the diamond crystal, the same material as a mined diamond. Moissanite is a diamond simulant, a different stone cut to look like a diamond; a lab-grown diamond is a diamond.
Which is better, moissanite or a lab-grown diamond?
A lab-grown diamond is the better stone: harder, whiter in its sparkle, graded by an independent lab and accepted as a diamond by every tester and appraiser. Moissanite is the better bargain: a one-carat look costs $225 to $375 against $640 for a lab-grown diamond in Clairamor's picker, and the gap widens with size. Choose by which of those matters more.
Can you tell moissanite from a diamond?
Usually, with a little attention. Moissanite throws rainbow flashes where a diamond's sparkle is mostly white, its facets look doubled under a 10x loupe, and a loose stone weighs about 9% less than a diamond of the same size. A jeweler confirms it in seconds with an electrical tester; a lab-grown diamond also carries a report number inscribed on its edge.
Does moissanite pass a diamond tester?
It passes the common heat-based pen tester, because moissanite conducts heat almost as well as diamond, which is how moissanite has been passed off as diamond. It fails an electrical or dual tester, because moissanite conducts electricity and, with rare exceptions, diamond does not. A lab-grown diamond passes every tester, since it is a diamond.
How much is a one-carat moissanite compared with a one-carat lab-grown diamond?
On September 25, 2026, a 6.5 mm round moissanite, the size of a one-carat diamond, was $225 unbranded and $375 as Charles & Colvard's Forever One; a one-carat round lab-grown diamond of D to G color and IF to VS2 clarity started at $640 in Clairamor's picker. At two carats the numbers were $300 to $750 for moissanite and $1,178 for the diamond.
What is the downside of moissanite?
Its sparkle is not a diamond's: more rainbow, softer facet edges, and in big stones and sunlight the disco-ball effect that people either love or cannot unsee. It is a little softer, it needs cleaning more often, it is graded only by its maker, it fails an electrical tester, and it resells for almost nothing. None of that is a defect; it is what a $300 stone is.
Is moissanite considered fake?
Moissanite is a real gemstone and a real mineral; it is not a fake anything unless it is sold as a diamond. The honest word is simulant. It only becomes a problem when a seller lets a buyer believe it is a diamond, or when a ring is passed down without anyone saying what is in it.
Does moissanite get cloudy?
The stone does not change, but it holds skin oil and soap film more visibly than a diamond, so an uncleaned moissanite looks dull sooner than an uncleaned diamond. A soft brush and warm soapy water bring either back. The green or yellow cast on older and cheaper moissanite is a color grade, not clouding, and does not wash off.
Is moissanite as hard as a diamond?
Nearly. Moissanite is 9.25 on the Mohs scale, harder than sapphire and ruby at 9; diamond is 10. Both are hard enough to wear every day for decades. The practical difference is that a diamond can scratch a moissanite, so store the two apart, and nothing but a diamond scratches a diamond.
Why is moissanite so cheap?
Because it is easy to grow, the patents that once limited it to a single maker expired in 2015, and there is no independent grading to pay for. Unbranded moissanite now sells for a few hundred dollars at any size; branded stones with a color grade and a warranty cost two to three times that. Lab-grown diamond prices have fallen too, which is why the gap between the two is now two to three to one rather than ten to one.
Does Clairamor sell moissanite?
No. Every ring Clairamor makes is set with a lab-grown diamond chosen from its picker, graded D to G and IF to VS2 by IGI or GIA, with the report number inscribed on the stone. Bring a moissanite to a consultation and we will tell you what it is; we will not set it as a diamond.
