Lab-Grown Diamond vs Moissanite

Diamond (whether natural or laboratory-grown) is pure carbon arranged in a cubic crystal lattice with sp3 bonding. Every atom in a diamond is a carbon atom, every bond is between two carbon atoms in tetrahedral geometry, and the resulting crystal is the hardest known naturally-occurring substance. The chemistry is documented in Chapter 1 and the laboratory growth methods in Chapter 2.

Moissanite is silicon carbide (SiC), a compound mineral containing both silicon and carbon atoms arranged in a hexagonal crystal lattice. Naturally occurring moissanite is extremely rare on Earth (first identified by Henri Moissan in 1893 in meteorite fragments) and essentially all moissanite in the jewellery market is laboratory-synthesised, primarily by Charles & Colvard's Forever One product line and several other manufacturers². The synthesis uses a different process from diamond growth and the resulting material is fundamentally different from diamond.

The chemistry difference matters because it produces different optical signatures, different hardness, and different identification characteristics. A laboratory can distinguish moissanite from diamond reliably with several methods (electrical conductivity testing, spectroscopy, double-refraction observation under microscopy), and a trained jeweller can distinguish them visually with experience. The materials are not interchangeable in any technical sense; they are two distinct gemstone categories that happen to resemble each other to the casual observer.

Diamond and moissanite produce visibly different optical effects despite their visual similarity at first glance. Diamond has a refractive index of 2.42, which produces strong brilliance (white-light return) when cut to standard proportions. Moissanite has a refractive index in the 2.65 to 2.69 range (the variation is because moissanite is birefringent, with two slightly different refractive indices depending on light direction), which produces brilliance that exceeds diamond's¹.

Dispersion (the splitting of white light into spectral colours, producing the rainbow flashes called 'fire' in diamond grading) differs more dramatically. Diamond's dispersion is 0.044; moissanite's is 0.104, roughly two and a half times higher¹. The result is that moissanite produces noticeably more rainbow flashes than diamond under varied lighting, which is one of the easier visual distinctions for a trained observer. A round-brilliant moissanite at one carat shows more pronounced colourful flashes than a round-brilliant diamond at one carat.

The optical difference is one reason moissanite is sometimes preferred by buyers who specifically want stronger sparkle and fire than diamond produces. It is also a reason some buyers prefer diamond's more restrained optical signature. The preference is aesthetic and personal; neither is objectively 'better,' but they are visibly different in side-by-side comparison.

Double refraction is the third distinguishing optical feature. Moissanite is birefringent, meaning light passing through the stone splits into two slightly offset rays. When viewed under magnification from certain angles, this produces a visible doubling of facet edges seen through the stone, which is a definitive identifier of moissanite versus diamond at the jeweller-counter inspection level. Diamond, with its isotropic cubic structure, does not show this doubling.

Diamond scores 10 on the Mohs hardness scale, the maximum value. Moissanite scores 9.25, second only to diamond among gemstones in routine jewellery use⁵. Both materials are very hard and suitable for everyday wear in engagement rings and other regularly-worn jewellery. The Mohs scale is logarithmic, and the practical difference between 9.25 and 10 is real but modest in everyday wearing terms.

In practical terms, a diamond ring worn daily for decades will not show surface scratches or abrasion damage; a moissanite ring worn under the same conditions will not either. Both materials resist common scratching agents (quartz dust, household chemicals, ordinary handling). The hardness difference matters mostly in laboratory or industrial settings where the materials are compared under controlled abrasion tests; for jewellery purposes, both are 'very durable.'

The brittleness profile is different from hardness. Diamond is the hardest material but is also brittle along certain crystal planes (cleavage planes), and a sharp impact at the right angle can chip or fracture a diamond despite its hardness. Moissanite has different fracture characteristics and may handle impact slightly differently. The practical implication is that both materials benefit from sensible setting design (V-prongs on shapes with sharp corners or points) and from avoiding extreme impacts (removing the ring during heavy manual work).

Moissanite sits at a substantially lower price tier than lab-grown diamond, which in turn sits below natural diamond. A one-carat-equivalent moissanite at the leading brand quality tier (Charles & Colvard Forever One) typically retails for the low hundreds of dollars; a one-carat lab-grown diamond at G VS1 Excellent IGI typically retails for the high hundreds to low thousands of dollars; a one-carat natural diamond at the same grade tier typically retails in the low to mid thousands of dollars.

The price hierarchy reflects the materials, the production methods, and the market positioning. Moissanite is a simulant material with its own market identity rather than a positioned alternative to diamond; lab-grown diamond is the same material as natural diamond at a different price tier. The buyer's choice between moissanite and lab-grown diamond is therefore a choice between two different gemstones, while the buyer's choice between lab-grown and natural diamond is a choice within the diamond category.

We do not publish specific retailer prices on this site because retailer pricing is promotional and varies widely. The category positioning above is broadly consistent across the major United States retailers in 2026.

The Federal Trade Commission Jewelry Guides (16 CFR Part 23) regulate how diamond, moissanite, and other gemstones may be named in commerce⁴. The key rules:

Lab-grown diamond may be called 'diamond' provided the qualifier 'laboratory-grown,' 'laboratory-created,' or '[manufacturer]-created' precedes the word 'diamond' and is displayed as conspicuously as the word 'diamond' itself. This rule was established in the 2018 revision of the Jewelry Guides and recognises that laboratory-grown diamonds are chemically and physically identical to natural diamonds. The full text and analysis is in Chapter 6.

Moissanite may not be called 'diamond' under any circumstances. Calling moissanite 'diamond' is a misleading-naming violation under FTC rules, regardless of qualifying language. Moissanite must be called 'moissanite' or, in some cases, 'silicon carbide.' Brand names (such as Forever One) may be used in addition to but not in place of the material identifier. The same rule applies to other diamond simulants: cubic zirconia must be called cubic zirconia, white sapphire must be called white sapphire, and so on.

The FTC rules require disclosure at point of sale, and reputable retailers comply consistently. A buyer purchasing moissanite from a mainstream United States retailer will be told the stone is moissanite, will see the moissanite identifier on the packaging and any certification, and will not be misled. The protection is structural rather than incidental, and applies to in-store, online, and catalogue sales.

The buyer's decision between lab-grown diamond and moissanite is a different decision from the lab-grown-versus-natural diamond decision. The lab-grown-versus-natural decision is within the diamond category and the choice is mostly values-and-resale driven. The lab-grown-versus-moissanite decision crosses category boundaries and the choice is values-and-identity driven: does the buyer want a diamond (in which case lab-grown is the cost-conscious choice) or are they comfortable with a non-diamond stone that resembles diamond visually (in which case moissanite is the cost-conscious choice).

For a buyer for whom the stone-is-diamond identity matters meaningfully (because of personal preference, partner expectation, narrative coherence, or social context), lab-grown diamond is the cost-conscious diamond option. The Bain category ratios apply, the FTC framework recognises the stone as diamond, and the visible quality is identical to natural at the same grade. Moissanite does not meet this requirement because it is not diamond.

For a buyer for whom the visible appearance matters more than the stone-is-diamond identity, moissanite is a legitimate and cost-effective option. The visual difference between moissanite and diamond is detectable to a trained observer but is not obvious to most casual observers, and a well-cut moissanite presents as a sparkling clear gemstone in an attractive setting. The buyer must accept the FTC disclosure that the stone is moissanite and accept the lower resale and recognition tier that moissanite occupies relative to diamond. Both are reasonable positions and the choice is personal.

Cross-references

For the FTC rules on diamond naming and disclosure, see Chapter 6. For the underlying diamond chemistry and growth methods, see Chapter 1 and Chapter 2. For identification equipment that distinguishes diamond from moissanite, see the tester appendix. For the lab-grown-versus-natural diamond comparison that is the main subject of this site, see the homepage and the chapter index.