If you are weighing up moissanite against a diamond, you are probably asking one blunt question: is it worth it, or is it just a cheap fake? Here is the honest answer from a jeweller who sells moissanite and does not sell diamonds.
The short version
Moissanite is not a diamond and we never call it one. It is a different gemstone — silicon carbide rather than carbon — with its own optical character. It is almost as hard, throws considerably more colour, and costs a fraction of the price. Whether that trade is worth making depends entirely on what you want from the stone.
Hardness: how it survives daily wear
On the Mohs scale, diamond is 10 and moissanite is 9.25. Sapphire, for comparison, is 9. That puts moissanite among the hardest gemstones you can buy and well clear of cubic zirconia at 8 to 8.5.
In practice this means a moissanite ring will not scratch from ordinary wear, will not cloud over, and does not need babying. It is a stone you can wear on a Tuesday.
Fire and brilliance: where moissanite wins
Moissanite has a refractive index of about 2.65 against a diamond's 2.42, and a dispersion of 0.104 against 0.044 — more than twice as much. Dispersion is the technical word for the rainbow flashes you see when a stone catches light. Jewellers call it fire.
So a moissanite throws noticeably more colour than a diamond of the same size. Some people love that. Some people find it too much and prefer the whiter, icier flash of a diamond. Neither is wrong, and it is the single biggest reason to look at a stone in real light before you buy — which is exactly why we show every piece in the hand on our live shows rather than relying on retouched studio photographs.
Price: the honest gap
This is the reason most people are reading this. A one-carat mined diamond of decent quality runs into thousands. A one-carat-equivalent moissanite set in sterling silver sits comfortably under a hundred pounds. You are not paying for rarity, because moissanite used in jewellery is created in a laboratory and is not rare.
What you are paying for is the cut, the setting, the metal and whoever stands behind it.
Does moissanite pass a diamond tester?
On a basic thermal tester, usually yes. Moissanite conducts heat almost identically to diamond, so a cheap pen tester will often read it as diamond. On a dual tester that also measures electrical conductivity, no — diamond conducts electricity and moissanite does not, so the two separate immediately.
We mention this because some sellers use the first fact to imply their stone is a diamond. It is not, and anyone telling you otherwise is misleading you. We are happy to demonstrate the test live and explain exactly what it does and does not prove.
Moissanite versus cubic zirconia
Worth separating, because they get lumped together. Cubic zirconia is softer (8 to 8.5), has roughly half the fire, and tends to cloud and dull within a year or two of regular wear. Moissanite does neither. The price difference between them is real but small compared to the difference in how they age.
So which should you buy?
Buy a diamond if the origin of the stone matters to you, if you want resale value, or if you specifically prefer a whiter flash.
Buy moissanite if you want maximum sparkle per pound, a stone that stands up to daily wear, and no anxiety about losing it. Most of our customers are buying their second or third piece rather than an heirloom, and that is exactly the job moissanite does well.