Quick answer
The short version of moissanite vs lab-grown diamond: a lab-grown diamond is a real diamond (pure carbon, hardness 10) made in a factory. Moissanite is a different gem (silicon carbide, hardness 9.25) with about 2.4 times the rainbow fire, and it costs much less. Choose a lab diamond if the word “diamond” matters to you. Choose moissanite for the most sparkle per dollar.
Both stones are grown above ground. Both look white and bright from across a room. Both cost far less than a mined diamond. That is where the likeness ends: one is a diamond, the other is its own gem, first found in a meteorite.
Below, we compare them on sparkle, hardness, color, price and resale, with the real numbers, so you can choose with a clear head.
Key takeaways
- A lab-grown diamond is chemically a diamond. Moissanite is silicon carbide, a separate gem.
- Moissanite throws more colored flashes (dispersion 0.104 vs 0.044). A diamond looks whiter and calmer.
- A diamond is harder (10 vs 9.25), but both handle daily wear well.
- Neither holds resale value. Buy the one you love, not an investment.
What is the difference between moissanite and a lab-grown diamond?
A lab-grown diamond is carbon crystallized as diamond, grown from a small seed crystal either under high pressure and heat (HPHT) or from a carbon-rich gas (CVD). According to GIA, it has nearly the same chemical, optical and physical properties as a mined diamond. That is why the US Federal Trade Commission dropped the word “natural” from its definition of diamond in 2018.
Moissanite is silicon carbide. French chemist Henri Moissan found tiny crystals of it in 1893, in fragments of the Canyon Diablo meteorite in Arizona, and first thought they were diamond. Natural moissanite is far too rare for jewelry, so every moissanite you can buy is lab-grown. Gem-quality stones reached jewelers in the late 1990s.
So the real question is not “real or fake”. Both are real, both are made in a lab. You are choosing between two different gems. For the full backstory, read Is moissanite real? or our moissanite guide.
Moissanite vs lab-grown diamond, side by side
Here are the numbers that matter, in one place. Every figure for moissanite applies to white stones; the Daellia line is D color, VVS1.
| Moissanite | Lab-grown diamond | |
|---|---|---|
| Material | Silicon carbide (SiC) | Carbon, same as a mined diamond |
| Hardness (Mohs) | 9.25 | 10 |
| Refractive index | 2.65 to 2.69 | 2.42 |
| Dispersion (fire) | 0.104 | 0.044 |
| Density | About 3.21 g/cm3, so about 10% lighter | About 3.52 g/cm3 |
| How it is sized | DEW (diamond equivalent weight) | Actual carat weight |
| Color | Colorless grades exist (Daellia: D, VVS1) | D to Z scale; GIA now says “premium” or “standard” |
| Thermal diamond tester | Reads as diamond | Reads as diamond |
| Resale value | Very low | Low and falling |
Sources: GIA, Britannica. Moissanite figures are for colorless stones.
Which sparkles more, moissanite or a lab diamond?
Moissanite does, by a clear margin. Two numbers explain why. The refractive index (how strongly a gem bends light) is 2.65 to 2.69 for moissanite versus 2.42 for diamond. The dispersion (how much it splits white light into color) is 0.104 versus 0.044, so moissanite shows about 2.4 times more rainbow fire.
What you actually see: under candlelight or direct sun, moissanite flashes pink, green and violet. A diamond flashes too, but its light reads whiter and calmer. The bigger the stone, the easier the fire is to spot. Neither look is better. If you want an icy, quiet glow, a lab diamond fits. If you love color in your sparkle, moissanite gives you more of it.
One honest note: moissanite is doubly refractive. At some angles, and under a loupe, you can see the back facet edges doubled. Good cutters orient the stone to keep this out of view, and most people never notice it.
Is moissanite as durable as a lab-grown diamond?
Almost. A lab diamond scores 10 on the Mohs scale. Moissanite scores 9.25, above sapphire and ruby (9) and well above cubic zirconia (about 8 to 8.5). The scale is not linear, though: Britannica notes that going from 9 to 10 means a jump of more than 300 percent in hardness. A diamond really is much harder to scratch.
In daily life, the gap matters less than it sounds. The grit in everyday dust includes quartz, at 7 on the scale, and quartz cannot scratch either stone. What wears first on any ring is the metal: prongs thin and plating softens over the years. Have prongs checked once a year and clean the stone often.
Moissanite does not cloud or fade. When it looks dull, it is a film of lotion, soap and skin oil, gone after a wash. See does moissanite get cloudy and our jewelry care guide.
Good to know
A standard thermal diamond tester reads moissanite as diamond. A multi-tester, which also measures electrical conductivity, tells the two apart. Telling lab from mined diamond takes specialized screening equipment. Details in does moissanite pass a diamond tester.
Lab-grown diamond vs moissanite price: what does 1 carat cost?
Lab-grown diamond prices have fallen hard. When De Beers launched its Lightbox lab-grown brand in 2018, it priced stones at $800 per carat; in 2025 it announced it would close the brand. Prices have kept sliding as production grows.
Finished rings cost far more than loose stones: The Knot's 2026 Real Weddings Study found 61% of couples chose a lab-grown center stone, and put the average lab-grown engagement ring at about $4,300.
Moissanite sits lower still. It is sold by DEW: a 6.5mm round looks like 1 carat but weighs about 0.88 ct. With moissanite, a complete ring, stone and metal included, can cost less than a loose lab diamond of the same size.
Moissanite solitaires to compare
Sirius Moissanite Solitaire RingClassic round in six prongs, 1ct to 5ct, sterling silver with white gold plating.See the piece
Olympe Oval Moissanite Engagement Ring2ct oval on a slim 14K gold filled band.See the piece
Sirius Moissanite Solitaire StudsThe easiest way to test the look, from 3mm to 9mm.See the piece
Do moissanite and lab-grown diamonds hold their value?
No, and neither one should be bought as an investment. Lab diamond production keeps growing, so a stone bought today competes with cheaper new stones tomorrow. When new stones keep getting cheaper, resale offers fall with them.
Rarity is gone too. Since October 1, 2025, GIA no longer uses its diamond color and clarity grades for lab-grown stones. Its reports now say “premium” or “standard”, because more than 95% of lab-grown diamonds fall into a very narrow range of color and clarity.
Moissanite has very little resale value as well. The difference is how much you put in. Spend less up front and there is less to lose. On ethics, both stones are grown, not mined, so neither involves digging. Both use a lot of electricity to make, so if that is your main concern, ask the seller where and how its stones are produced.
Moissanite or lab-grown diamond: which should you buy?
Decide by what matters most to you. Here is the honest version, one priority per row.
| If you care most about | Choose | Why |
|---|---|---|
| The word “diamond” | Lab-grown diamond | It is chemically a diamond |
| Maximum sparkle and fire | Moissanite | About 2.4 times the dispersion |
| The hardest stone possible | Lab-grown diamond | 10 on Mohs versus 9.25 |
| The biggest look for your budget | Moissanite | A full ring can cost less than a loose lab stone |
| A calm, white glow | Lab-grown diamond | Less colored flash |
| Everyday studs you will not worry about | Moissanite | Size up freely; a lost stud costs less to replace |
| Resale value | Neither | Both resell for a small fraction of the price |
Still torn? Try the look before the big purchase. A pair of Sirius moissanite studs (3mm to 9mm) shows you how moissanite fire looks on you, every day, for a small part of a ring budget. For rings, browse our moissanite engagement rings, or read the moissanite engagement ring guide first. Check your size with the ring size guide.
A lab diamond is a diamond. Moissanite is a different gem. Both can be the right choice, as long as you know which one you are buying.The Daellia Journal
Find your solitaire
Round, oval or emerald cut, in sterling silver or 14K gold filled. Every white stone is D color, VVS1 moissanite.
Shop engagement ringsFrequently asked questions
Can people tell moissanite from a lab-grown diamond?
Rarely at a glance. From a normal distance both read as bright white stones. Up close in sunlight, moissanite shows more rainbow flashes, and under a loupe you may see doubled facet edges. A jeweler with a multi-tester can confirm it in seconds, because moissanite conducts electricity differently from diamond.
Is a lab-grown diamond a real diamond?
Yes. A lab-grown diamond is crystallized carbon with nearly the same chemical, optical and physical properties as a mined diamond, which is why the FTC removed the word “natural” from its definition of diamond in 2018. It must be sold as lab-grown, and GIA laser-inscribes the ones it assesses as laboratory-grown.
Is moissanite or a lab-grown diamond better for an engagement ring?
Both work for daily wear. Choose a lab-grown diamond if you want a diamond and a softer, whiter sparkle. Choose moissanite if you want more fire and a bigger stone for the same budget. Moissanite at 9.25 on the Mohs scale is harder than sapphire, a classic engagement stone.
Does moissanite get cloudy over time?
No. Moissanite does not cloud, fade or change color. When it looks dull, it is a film of oils, lotion and soap on the surface. Soak it in warm water with a drop of mild dish soap, brush gently with a soft toothbrush, rinse and dry, and the sparkle comes straight back.
Do lab-grown diamonds and moissanite pass a diamond tester?
A lab-grown diamond passes every diamond tester, because it is a diamond. Moissanite passes a standard thermal tester too, since it moves heat much like diamond does. A multi-tester that also checks electrical conductivity flags moissanite. Separating lab from mined diamond needs specialized screening devices such as GIA's iD100, or a lab report.
Keep reading
Written by the Daellia Journal team, Paris. We write about moissanite, metals and the stories behind fine jewelry so you can buy with confidence. Read our moissanite guide or our story.
