Moissanite occupies an odd position in the jewellery market. It is the stone people buy when they have decided not to buy a diamond, and then spend the next several years explaining. It is also the stone most often misdescribed by both its advocates and its critics, usually by people who have a financial interest in one answer.
The honest position is straightforward. Moissanite is a genuinely good gemstone with real optical advantages and real drawbacks. It is not a diamond substitute in any meaningful sense — it is a different stone with different light behaviour — and the decision between them is a decision about what you value, not about which one is better.
This is what the differences actually are, what they cost in 2026, and where the case for moissanite falls down.
What moissanite actually is
Moissanite is silicon carbide, SiC — a compound of silicon and carbon that occurs naturally in extremely small quantities. It was identified in 1893 by the French chemist Henri Moissan, who found it in fragments of the Canyon Diablo meteorite in Arizona. He initially believed he had found diamond; he had not. Natural silicon carbide is vanishingly rare and never of gem quality.
Every moissanite sold as a gemstone is synthesised. The modern material is produced by a process that grows large single crystals of silicon carbide, developed commercially in the 1990s and refined considerably since. There is no such thing as a mined gem-quality moissanite on the market, and any seller implying otherwise is either confused or misleading you.
This is worth stating clearly because it frames the entire ethical argument. Moissanite is not "natural" in the sense that a mined diamond is. It is a manufactured material, and its environmental and ethical case rests on the same foundations as lab-grown diamond: no mining, no land disturbance, no labour risk, and energy consumption that depends entirely on how the growing facility is powered.
Key properties, for comparison:
| Property |
Moissanite (SiC) |
Diamond (C) |
| Refractive index |
2.65–2.69 |
2.417 |
| Dispersion (fire) |
0.104 |
0.044 |
| Mohs hardness |
9.25 |
10 |
| Specific gravity |
3.21–3.22 |
3.52 |
| Cleavage |
None |
Perfect octahedral |
| Birefringence |
0.043 (doubly refractive) |
None (singly refractive) |
| Thermal conductivity |
High |
Very high |
| Electrical conductivity |
Yes |
No (except rare type IIb) |
Two rows in that table matter more than the rest. The dispersion figure explains why moissanite looks the way it does. The birefringence figure explains how it is identified.
The optical differences, honestly
Refractive index
Moissanite's refractive index of 2.65–2.69 is higher than diamond's 2.417, which means it bends light more and has a higher theoretical brilliance. In practice, the difference is less visible than the number suggests, because brilliance also depends on cut quality, and a poorly cut moissanite will be outperformed by a well-cut diamond every time.
What the higher refractive index does mean is that moissanite has a slightly different character in the hand — a bit more "wattery," with a somewhat higher contrast between bright and dark areas in the facet pattern. Under certain lighting it can look slightly glassy in a way diamond does not.
Dispersion — the fire, and the real dividing line
Dispersion is the property that splits white light into its spectral components, producing the flashes of colour known as fire. Moissanite's dispersion is 0.104. Diamond's is 0.044. That is roughly 2.4 times more.
The result is unmistakable. A moissanite in sunlight or under a single strong spotlight throws rainbow flashes — distinct greens, reds, oranges and blues — in a way that diamond simply does not. Diamond's fire is subtler and more white, which is one reason a diamond can look cooler and more restrained and moissanite can look livelier and, to some eyes, louder.
This is the whole decision, for most buyers. Some people see moissanite's rainbow and think it is beautiful and that diamond looks flat by comparison. Others see the same stone and think it looks like a disco ball, or that the colour flashes read as synthetic. Neither reaction is wrong, and no photograph conveys it properly. If you are considering moissanite, look at one in daylight before you commit.
The double refraction
Moissanite is doubly refractive, with a birefringence of 0.043. This is a large value, and it means that light entering the stone is split into two rays travelling at different speeds. The practical effect is that the stone's facet edges appear doubled under magnification.
This matters in two ways. Commercially, it is the definitive identification test — a loupe and a steady hand will show it. Aesthetically, it can occasionally cause a slightly blurry or "doubled" look at the junctions between facets on a large stone, visible to a careful eye without magnification. Most people never notice it. A gemmologist will see it immediately.
Hardness and toughness
Moissanite is Mohs 9.25. Diamond is 10. On the Mohs scale the gap between 9.25 and 10 is large in absolute terms — diamond is roughly four times harder than corundum at 9, and moissanite sits between them, closer to corundum than the number suggests.
For practical purposes, the distinction is nearly meaningless. Both stones resist scratching by anything you are likely to encounter in daily life. The only common material that will scratch either one is the other, and diamond is the only thing that will scratch moissanite.
The more important difference is toughness, and here diamond wins clearly. Diamond has perfect octahedral cleavage — it can split along crystal planes under a sharp blow — but it is extremely resistant to general chipping and abrasion. Moissanite has no cleavage, which is an advantage, but it is a brittle material: it chips more readily at facet edges and at the girdle under impact.
In practice this means a moissanite ring worn daily is fine, but a moissanite in a high prong setting that gets knocked against doorframes and countertops will show edge wear and occasional small chips sooner than a diamond would. In a bezel or a protective setting, the difference narrows considerably.
A note on treatments
Neither moissanite nor diamond is routinely treated, but both are routinely misrepresented. Moissanite is sometimes sold as "lab-grown diamond" by sellers who do not understand the difference or hope you do not. They are different minerals, and the price difference is large. Ask what the stone is in writing.
Colour
Early moissanite had a distinct greenish or yellowish cast that was its most recognisable flaw. Modern material has improved dramatically. Current production is graded on a scale roughly parallel to diamond colour, with the top grades approaching colourless and most commercial material sitting in the equivalent of a G-to-J range.
Two practical points. First, colour in moissanite is a grading convention applied by the manufacturer and the vendor, not an independent laboratory grade, so it is less reliable than a GIA diamond colour grade. Buy from a vendor who shows the stone in daylight and offers returns. Second, moissanite's colour can appear slightly different under different lighting, with a greenish undertone showing in some fluorescent environments and disappearing in daylight.
Fancy-coloured moissanite exists in a range of greens, blues, yellows and pinks. These are produced deliberately and can be attractive, but they should be understood as a manufactured colour rather than a natural one.
What they cost in 2026
The pricing picture has changed a great deal in the last few years, and the change is the most important thing in this article after the dispersion discussion.
| Stone, 1.00 ct round, good cut |
Typical 2026 retail |
Relative to natural diamond |
| Natural diamond, G/VS2 |
$4,500–$7,500 |
Baseline |
| Lab-grown diamond, G/VS2 |
$400–$900 |
90% less |
| Moissanite, near-colourless |
$250–$600 |
92–95% less |
Read that table twice, because it changes the decision. Moissanite is still cheaper than lab-grown diamond, but the gap has narrowed to the point where a one-carat stone is a few hundred dollars either way. What used to be an order-of-magnitude difference is now roughly a factor of one and a half.
The consequence is that the argument for moissanite has shifted. It is no longer primarily a price argument at one carat, because lab-grown diamond now occupies almost the same territory. At larger sizes the gap widens — a 3-carat moissanite is still a few thousand dollars against $8,000 or more for a comparable lab-grown — but the entry-level comparison is now much closer than moissanite's advocates usually acknowledge.
Where moissanite still wins decisively on price is at size. A 4-carat near-colourless moissanite can be bought for well under $3,000, while a lab-grown diamond of the same size and quality runs several times that. If you want a large stone and the budget is fixed, moissanite is the only way to get there.
For a fuller comparison of the two diamond categories, see our lab-grown versus natural diamond guide.
Resale
Moissanite has essentially no resale market. This is not a criticism of the stone; it is a fact about how the secondhand trade works.
The reasons are structural. Moissanite is a manufactured material whose supply is unlimited and whose production cost keeps falling, so there is no scarcity to support a secondhand price. There is no certification market, no dealer network competing for inventory, and no consumer confidence about what a used stone is worth. Most jewellers will not buy moissanite back at all, and those who will typically offer a token amount.
For comparison: natural diamond resells for roughly 20 to 50 percent of retail, depending on quality and where you sell it. Lab-grown diamond resells for close to nothing, for the same structural reasons as moissanite. If resale value matters to you, none of the three is a good store of value at retail prices, and moissanite is the weakest of the three.
This should inform how you think about the purchase. A moissanite ring is an expense, like a good coat. If the idea of a ring as an asset matters to you, buy a used natural diamond rather than a new moissanite — the used diamond has already taken its depreciation hit.
The ethical and environmental framing
Moissanite's environmental case is real but should be stated accurately rather than repeated as marketing.
Advantages. No mining, therefore no open-pit or underground extraction, no tailings, no habitat displacement at the source. No conflict-financing risk, because there is no artisanal mining sector involved. Supply is not concentrated in a way that funds armed groups.
The caveats. Silicon carbide is an energy-intensive material to grow, and its environmental footprint depends heavily on the electricity source powering the facility. A moissanite grown using coal-fired power has a very different footprint from one grown with hydroelectric or solar power, and manufacturers rarely publish this information in a verifiable form. There is also no independent certification body for moissanite comparable to the Kimberley Process for rough diamonds — which is itself imperfect, but at least exists and is auditable.
The honest summary: moissanite avoids the specific harms of mining, which are significant and well documented. It does not automatically have a low carbon footprint, and any brand claiming a specific carbon figure should be able to show you the methodology. We cannot verify those claims, and neither can you, which is a reason to treat them with appropriate caution.
How to tell moissanite from diamond
There are two reliable tests and one unreliable one.
The reliable test: double refraction. Under a loupe at 10x magnification, look at the facet edges through the crown. Diamond is singly refractive, so facet junctions are crisp single lines. Moissanite is doubly refractive with a birefringence of 0.043, so facet edges and any inclusions appear doubled — two parallel lines where there should be one. On a larger stone this is visible with a decent loupe and a steady hand. It is the classic gemmological identification and it does not require a laboratory.
The reliable test: electrical conductivity. Silicon carbide conducts electricity. Diamond does not, with the rare exception of type IIb stones, which are blue and extremely valuable and not what you are likely to be handling. A combined tester that measures both thermal and electrical conductivity will identify moissanite instantly and correctly.
The unreliable test: a cheap thermal probe. This is where most confusion originates. Diamond has extraordinarily high thermal conductivity, and cheap "diamond testers" work by measuring exactly that. But silicon carbide also has high thermal conductivity — not as high as diamond, but high enough that some thermal-only testers will report moissanite as diamond. If your jeweller tests a stone with a thermal pen and declares it diamond, that is not conclusive. Ask for a combined tester or a loupe check.
A note on how we work here: this site does not operate a laboratory and does not test stones. The identification methods described above are the standard techniques, but a definitive identification for any stone of value should come from a recognised gemmological laboratory. We describe the framework; we cannot certify your stone.
Who should buy moissanite, and who should not
Buy moissanite if: you want a large stone and the budget will not stretch to a comparable lab-grown diamond; you genuinely like the rainbow fire and prefer it to diamond's more restrained look; you are uncomfortable with mining and do not want a lab-grown diamond either; you want a stone for a piece you will wear hard and do not want to worry about it; or you are buying a travel or secondary ring.
Do not buy moissanite if: you want a stone that will hold value, because it will not; you want the optical restraint of diamond, because moissanite does not have it and no cut will give it to you; you would be bothered by the knowledge that the stone is manufactured, because that discomfort does not fade; or you are buying it as a substitute for a diamond you actually wanted, which is a decision that tends to age badly.
The last point deserves emphasis. The most common unhappy moissanite purchase is not a stone that disappointed on inspection. It is a buyer who wanted a diamond, could not afford one, bought moissanite instead, and then spent years feeling that the ring was a compromise. If you want a diamond, buy a smaller lab-grown diamond or a used natural one. Moissanite is a good stone in its own right, and buying it as a stand-in is unfair to the stone.
Durability and warranty
Most moissanite is sold with a warranty from the manufacturer or the brand. These typically cover the stone against defects in the material and sometimes offer replacement if the stone is damaged, but they almost universally exclude damage caused by impact, misuse or normal wear — which is exactly the category that includes the chips moissanite is most prone to.
Read the warranty terms rather than the headline. Specifically check: whether it covers chipping and abrasion or only manufacturing defects; whether it requires servicing by the seller at set intervals to remain valid; whether it survives a change of ownership if you give the ring away; and whether the "replacement" is a stone of equivalent quality or a credit against a new purchase.
A warranty that requires annual paid inspections to stay valid is not a warranty in any useful sense, and it is common in this category.
Where the moissanite case fails
Three honest problems, stated plainly.
The brittleness is real and underplayed. Moissanite marketing tends to emphasise hardness and skip toughness. A moissanite ring worn daily in a prong setting will accumulate edge chips over years, particularly on the girdle, and those chips cannot be polished out without recutting. In a bezel this is largely a non-issue. In a high four-prong setting on an active hand, it is a genuine risk.
The colour grading is not independent. Diamond colour is graded by third-party laboratories with published standards and consistent methodology. Moissanite colour is graded by the people selling it. There is no GIA equivalent, which means "near-colourless" from one vendor may not match "near-colourless" from another. Buy on the stone you can see, with a return policy, not on the grade.
The price advantage is narrowing. As lab-grown diamond prices have collapsed, moissanite's core commercial argument has weakened at small sizes. At one carat the difference is a few hundred dollars. The case for moissanite is now strongest at large sizes and for buyers who actively prefer the optical character — not for buyers simply looking for the cheapest white stone.
Frequently asked questions
Does moissanite look fake?
Not in the way people mean. It looks different — brighter, with more coloured fire and a rainbow effect that diamond does not produce. Whether that reads as fake depends on what you are comparing it to and who is looking. Most people cannot identify a well-cut moissanite in a setting at conversational distance. Under a loupe, the facet doubling is obvious to anyone who knows what they are seeing.
Is moissanite as durable as diamond?
No, but it is close enough for most wear. Moissanite is Mohs 9.25, so only diamond scratches it, and it has no cleavage. It is, however, more brittle than diamond, which means it can chip at the girdle or at facet edges under a hard impact. For a ring worn daily with normal care, a moissanite will hold up well. For a stone worn in a high-risk setting or knocked regularly, diamond is tougher.
Why does moissanite have more fire than diamond?
Because its dispersion is much higher — 0.104 against diamond's 0.044. Dispersion is the property that splits white light into spectral colours, so moissanite produces roughly two and a half times the coloured fire of diamond. It is a genuine optical difference, not a defect, and it is the single thing people either love or dislike about the stone.
Does moissanite hold its value?
No. Moissanite has essentially no resale market. A stone bought at retail will typically resell for a small fraction of what was paid, if it sells at all, and most jewellers will not buy it back. Treat moissanite as a consumable purchase rather than an asset, exactly as you would treat a lab-grown diamond, whose resale value is also close to zero.
How can a jeweller tell moissanite from diamond?
Two ways. Moissanite is doubly refractive, so under a loupe you can see doubled facet edges and doubled inclusions that diamond never shows. And silicon carbide conducts electricity, while diamond does not, so a combined thermal-and-electrical tester identifies it instantly. A cheap thermal-only tester can be fooled, because moissanite conducts heat much like diamond does.
The bottom line
Decide what you actually want before you decide what to buy, because this comparison has no single winner.
If you want the optical restraint, the hardness and the small but real resale value of diamond, buy a diamond — and if the budget is the constraint, buy a smaller lab-grown diamond rather than a moissanite. A well-cut 0.75-carat lab-grown stone in a good setting will cost less than $1,000 in 2026 and will be the thing you actually wanted. For setting options that make a smaller stone read larger, see our engagement ring styles guide.
If you want a large stone, like the rainbow fire, and are buying this as an expense rather than an investment, buy moissanite — near-colourless, in a bezel or half-bezel setting, from a vendor with a genuine return policy, and look at it in daylight first. Expect to pay $250 to $600 for a one-carat stone and under $3,000 for four carats, and accept that its resale value is zero.
Do not buy moissanite as a consolation prize. It is a good gemstone with a specific optical character, and it deserves to be chosen for that character rather than settled for. Buy it because you looked at one in the sun and liked what you saw. That is the only test that matters, and it is also the only one that predicts whether you will still like it in ten years.
