Moissanite is a naturally occurring silicon carbide gemstone, now produced in laboratory conditions for use in fine jewellery. It is not a diamond simulant, not cubic zirconia, and not an imitation stone. Moissanite is its own gemstone with its own chemical composition, its own optical properties, and its own certification standard. This guide covers everything a South African buyer needs to know.
Moissanite was first discovered in 1893 by French chemist Henri Moissan inside a meteorite crater in Arizona. The mineral he found was silicon carbide, a compound that does not occur naturally on earth in gem-quality quantities. What Moissan identified in that crater was later named moissanite in his honour.
Every moissanite used in jewellery today is laboratory-created. The same silicon carbide compound is grown under controlled conditions to produce gem-quality stones with consistent colour, clarity, and optical properties. The result is a gemstone that is neither mined nor artificially scarce.
Moissanite's laboratory origin is fully disclosed and documented on every GRA certificate. There is no deception in its origin story and no attempt to pass it off as something it is not.
Moissanite is silicon carbide. Diamond is carbon. They are chemically different compounds, which is why moissanite and diamond behave differently under a diamond tester, why they have different refractive indices, and why moissanite produces more coloured fire than diamond. Understanding this distinction matters because it prevents unrealistic expectations in either direction.
Moissanite's chemical formula is SiC. This distinguishes it from diamond (pure carbon), cubic zirconia (zirconium dioxide), and white sapphire (aluminium oxide).
All gem-quality moissanite is produced in laboratory conditions. This ensures consistent quality, eliminates mining impact, and allows precise control over the finished stone's characteristics.
Every moissanite stone used by Moissanite by Design carries a GRA certificate documenting its composition, origin, cut grade, and quality characteristics.
Moissanite is not a diamond simulant. It is a distinct gemstone with its own properties, its own certification, and its own identity in the fine jewellery market.
Hardness in gemstones is measured on the Mohs scale, which runs from 1 (talc) to 10 (diamond). A stone needs to score at least 7 to be considered suitable for daily wear in a ring. Moissanite scores 9.25, making it one of the hardest gemstones available and more than capable of withstanding decades of everyday use.
Moissanite scores 9.25 on the Mohs hardness scale. Diamond scores 10. Every other gemstone commonly used in engagement rings scores lower than moissanite.
Moissanite by Design — Hardness GuideMoissanite's hardness rating places it above sapphire (9.0), ruby (9.0), and all other gemstones except diamond. It will not scratch under normal daily wear conditions.
A gemstone can only be scratched by something harder than itself. For moissanite, that means only diamond. This makes moissanite highly resistant to surface scratching from everyday contact with other materials.
Hardness measures scratch resistance. Toughness measures resistance to chipping and breaking. Moissanite rates very good for toughness, meaning it handles the knocks and impacts of daily wear without fracturing.
Moissanite is highly resistant to heat, which matters during jewellery repairs and resizing. It will not discolour or crack under the heat exposure required for standard jewellery workshop procedures.
A well-set moissanite in a properly maintained ring will retain its optical properties indefinitely. The stone does not degrade, cloud, or lose its brilliance over time.
Moissanite can be cleaned with standard jewellery cleaning methods including ultrasonic cleaners, steam, and mild soap. It does not require special handling or protective storage beyond normal fine jewellery care.
Brilliance refers to the white light reflected from a gemstone. Fire refers to the coloured light dispersed as white light splits into its spectrum. Moissanite has a higher refractive index than diamond, which means it bends and reflects light more intensely. It also has a higher dispersion rate, meaning it produces more coloured fire than diamond under the same lighting conditions.
This is the defining visual characteristic of moissanite. In direct sunlight or under strong artificial light, the rainbow flashes of fire are more pronounced than those seen in diamond. Whether this is a feature or a drawback depends entirely on the buyer's preference, and it is something Lorna discusses with every client during consultation.
Diamond's refractive index is 2.42. Moissanite's is 2.65. The higher the refractive index, the more light is bent and returned to the eye as brilliance.
Moissanite has a dispersion rate of 0.104. Diamond's is 0.044. This means moissanite produces significantly more coloured fire, particularly visible in direct sunlight.
The brilliance pattern in moissanite differs from diamond due to its double refractive structure. Under magnification or in strong light, this can be visible as a slightly different sparkle pattern to those familiar with diamond.
Like all gemstones, moissanite's optical performance is heavily influenced by cut quality. A well-cut moissanite will maximise light return. A poorly cut stone will not perform to its potential regardless of its other characteristics.
Some shapes display more fire than others. Round brilliant and cushion cuts tend to show the most fire. Elongated shapes like oval and emerald cut show a different brilliance character that some buyers prefer for its subtlety.
Moissanite's fire is most pronounced in direct sunlight and under strong single-source lighting. In diffused indoor lighting it appears more similar to diamond. This is worth understanding before committing to a stone choice.
GRA stands for Gemological Research Association. The GRA certificate is the standard third-party verification document for laboratory-created moissanite, equivalent in function to IGI or GIA certification for diamonds. Every moissanite stone used in a Moissanite by Design commission carries a GRA certificate.
The GRA certificate documents the stone's composition as silicon carbide, its origin as laboratory created, its cut grade, colour grade, and overall quality assessment.
GRA certification is issued by an independent gemological body with no financial interest in the sale. The certificate provides third-party confirmation of what the client is buying.
GRA certificates include a hologram security feature that prevents duplication and confirms the certificate is genuine.
Each GRA certificate is tied to a specific stone via a unique reference number. This allows the certificate to be matched to the stone it was issued for.
Moissanite by Design provides the GRA certificate with every moissanite commission. The client receives the physical certificate alongside their finished piece.
Certification matters because it converts a verbal claim about a stone's quality into a documented, independently verified record. It gives the client something they can check, store, and refer to.
Moissanite and diamond are different gemstones. Understanding the differences honestly, without either overstating or understating them, allows buyers to make decisions they will be satisfied with long after the ring is delivered.
Diamond is carbon. Moissanite is silicon carbide. Diamond scores 10 on the Mohs scale. Moissanite scores 9.25. Diamond has a refractive index of 2.42. Moissanite has a refractive index of 2.65. Diamond produces less coloured fire. Moissanite produces more. A mined diamond of equivalent visual size to a moissanite will cost significantly more. A lab-grown diamond will cost less than mined but typically more than moissanite.
The choice between moissanite and diamond is not a quality decision. It is a preference decision. Both are durable, beautiful, and suitable for a lifetime of daily wear. The full moissanite vs diamond comparison covers every metric in detail.
Read the full moissanite vs diamond comparison, explore custom moissanite engagement rings for South Africa, or browse the Moissanite by Design journal for in-depth buying guides on every aspect of choosing a stone.
Is moissanite a real gemstone?
Yes. Moissanite is a real gemstone with its own chemical composition, silicon carbide, its own hardness rating of 9.25 on the Mohs scale, and its own certification standard via GRA. It is not a diamond simulant or an imitation stone.
Is moissanite the same as cubic zirconia?
No. Cubic zirconia is zirconium dioxide. Moissanite is silicon carbide. They are entirely different materials. Cubic zirconia is much softer, with a Mohs hardness of around 8, and loses its optical clarity over time. Moissanite does not.
Will moissanite pass a diamond tester?
Most standard diamond testers test for thermal conductivity, and moissanite conducts heat similarly to diamond, so it may read as diamond on basic testers. Advanced testers that test both thermal and electrical conductivity will correctly identify moissanite.
Does moissanite look like diamond?
Moissanite is visually similar to diamond in most settings and lighting conditions. The main visible difference is that moissanite produces more coloured fire, particularly visible in direct sunlight. In diffused indoor lighting the two appear very similar.
How hard is moissanite?
Moissanite scores 9.25 on the Mohs hardness scale. Diamond scores 10. This makes moissanite harder than sapphire, ruby, and all other gemstones commonly used in fine jewellery. It is more than suitable for daily wear in an engagement ring.
Does moissanite come with a certificate?
Yes. Every moissanite stone used by Moissanite by Design carries a GRA certificate issued by the Gemological Research Association. The certificate documents the stone's composition, origin, cut grade, and quality characteristics.
Share your brief, your budget, and your stone preference. Lorna will guide you through every choice from cut and shape to setting and metal.
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