Moissanite vs Diamond in South Africa: Honest 2026 Comparison
Last updated: June 2026 | Independently researched by Diamond Guide SA
Moissanite is not a diamond. It is silicon carbide, a separate gemstone that looks like a diamond to the naked eye but costs a small fraction of one. Against a real diamond it is slightly softer (Mohs 9.25 vs 10), noticeably more fiery (it throws more rainbow flashes), and dramatically cheaper. A 1 carat moissanite runs roughly R3,000 to R9,000 in SA, versus R12,000 to R30,000 for a lab-grown diamond and R75,000 plus for a GIA-certified natural diamond. The trade-off is resale: moissanite holds almost no value, while a natural diamond retains 30 to 50 per cent. This guide explains the real differences and when each one is the right call.
Moissanite vs diamond at a glance
What is moissanite?
Moissanite is silicon carbide (SiC), first discovered by the chemist Henri Moissan in a meteorite crater in 1893. Natural moissanite is vanishingly rare, so every moissanite sold for jewellery is lab-created. Because it is a different mineral from diamond, it is classed as a diamond simulant: a stone that imitates the look of a diamond without being one. This is the key distinction from a lab-grown diamond, which is chemically a real diamond. As Prodiam, a Bedfordview cutting house, sets out in its natural, lab-grown and moissanite guide, these are three different products with three different value curves, and none of them is fake.
Because moissanite is less dense than diamond, it is sold by millimetre size or by “diamond equivalent weight” (DEW) rather than true carat weight. A stone described as 1 carat moissanite is really the 6.5 mm size of a 1 carat diamond. The best-known quality brand is Charles & Colvard (Forever One), though many unbranded options are sold in SA.
Moissanite vs natural vs lab-grown diamond
| Property | Moissanite | Natural diamond | Lab-grown diamond |
|---|---|---|---|
| Material | Silicon carbide (SiC) | Carbon (C) | Carbon (C), real diamond |
| Hardness (Mohs) | 9.25 | 10 | 10 |
| Refractive index | 2.65 (more brilliant) | 2.42 | 2.42 |
| Fire (dispersion) | 0.104 (rainbow flashes) | 0.044 | 0.044 |
| Light behaviour | Doubly refractive | Singly refractive | Singly refractive |
| Price (1 ct / 6.5 mm) | R3,000 - R9,000 | R75,000 - R95,000 | R12,000 - R30,000 |
| Resale value | Effectively none | Retains 30-50% of retail | Limited, falling |
| Certification | Brand report (e.g. C&C) | GIA (gold standard) | GIA / IGI |
| Is it a diamond? | No (simulant) | Yes | Yes |
How to tell moissanite from a diamond
To the naked eye the two are hard to separate, which is the whole appeal of moissanite. Up close there are reliable tells. Moissanite throws noticeably more coloured fire, which becomes obvious in stones above about 1 carat and can read as a disco-ball flash that diamonds do not produce. Under 10x magnification, moissanite shows doubled facet edges because it is doubly refractive; a diamond never does this. A moissanite-specific tester (which measures electrical conductivity) separates the two instantly, where an older thermal-only diamond tester is fooled because moissanite conducts heat much like a diamond.
When does each one make sense?
Moissanite suits you if:
- + You want maximum sparkle and size for the lowest possible price
- + You like extra rainbow fire and do not mind it being flashier than a diamond
- + It is a fashion piece, a travel ring, or a placeholder
- + Resale value and long-term investment are not a concern
A real diamond suits you if:
- + You want the genuine article for an engagement or milestone
- + Value retention, resale and heirloom potential matter
- + You prefer the subtler white sparkle of a diamond to heavy rainbow fire
- + You want GIA certification you can independently verify
If you decide you want a real diamond rather than a simulant, the choice narrows to lab-grown versus natural, covered in full in our lab-grown vs natural diamond guide. For a natural diamond at the keenest Rand price, a wholesale-to-public cutting house such as Prodiam in Bedfordview prices GIA-certified stones 30 to 40 per cent below retail, and you can brief its bench to source a specific stone. Size any option to scale first on the diamond size calculator.
Guidance and sources
Frequently Asked Questions
Is moissanite a real diamond?
No. Moissanite is silicon carbide, a different mineral from diamond (pure carbon). It is a diamond simulant that looks similar to the eye. Lab-grown diamonds are real diamonds; moissanite is not.
What is the difference between moissanite and a diamond?
Material (silicon carbide vs carbon), hardness (9.25 vs 10), and fire (moissanite throws more than double the rainbow flash). The largest practical difference is price: moissanite costs roughly 90 per cent less than a natural diamond, with almost no resale value.
How much does moissanite cost in South Africa?
A 1 carat (6.5 mm) moissanite is roughly R3,000 to R9,000, against R12,000 to R30,000 for an equivalent lab-grown diamond and R75,000 plus for a GIA-certified natural diamond.
Does moissanite pass a diamond tester?
It passes an older thermal tester because it conducts heat like a diamond, but fails a moissanite tester that reads electrical conductivity. Under magnification its doubled facet edges give it away.