Lab-Grown Diamonds vs Moissanite: How to Choose
Lab-grown diamonds and moissanite are the two most popular diamond alternatives, and both offer brilliant sparkle for far less than a mined diamond. But they are not the same thing: one is a genuine diamond grown in a laboratory, the other is a separate gemstone with its own distinctive look. Here is how they compare so you can choose the right stone for your ring.
A lab-grown diamond is a real diamond – identical carbon structure, 10 on the Mohs scale, graded by IGI or GIA. Moissanite is silicon carbide, slightly softer at 9.25, and throws far more rainbow fire, which some love and others find showy. Moissanite is usually the cheaper option; a lab-grown diamond is the choice if you specifically want a certified diamond in your engagement ring.
What each stone actually is
A lab-grown diamond is chemically, physically and optically identical to a natural diamond; only its origin differs. It is created using HPHT or CVD technology and graded on the same 4Cs. Learn the essentials in our beginner's guide to lab-grown diamonds.
Moissanite is made of silicon carbide. It occurs in nature only in tiny quantities in meteorites, so virtually all jewellery moissanite is lab-created. It is a beautiful, hard-wearing gemstone, but it is a diamond alternative rather than a diamond.
Hardness and durability
Diamond tops the Mohs scale at 10, making a lab-grown diamond the most scratch-resistant option for everyday wear. Moissanite is close behind at 9.25 – harder than a sapphire and perfectly suitable for daily use – but marginally less durable over a lifetime of knocks.
Sparkle, fire and colour
This is where they differ most. Moissanite has a dispersion of about 0.104, more than double a diamond's 0.044, so it flashes intense rainbow colours – an effect that becomes very noticeable in larger stones and under bright light. A lab-grown diamond gives the classic, balanced white-and-coloured sparkle people expect from a diamond. On colour, moissanite can show a faint yellow or greyish tint as size increases, whereas a well-chosen lab-grown diamond stays colourless. For a deeper comparison, see our post on moissanite vs diamond.
Price in the UK
Moissanite is typically the most affordable of the three options: a one-carat-equivalent moissanite often costs somewhere around £200–£500 as a loose stone. A certified one-carat lab-grown diamond generally starts from about £600–£1,200 depending on quality, while a comparable mined diamond can run to several thousand pounds. To see how lab-grown compares with natural on price, use our price comparison guide.
Which is right for you?
Choose moissanite if you want maximum sparkle and size for the smallest budget and you like its extra fire. Choose a lab-grown diamond if it matters to you that the centre stone is a real, certified diamond with a lifetime of colourless brilliance. Many couples weighing this decision also read our guide to diamond engagement rings vs moissanite, and browse our diamond education resources before deciding.
Frequently asked questions
Will a diamond tester detect moissanite? Standard thermal testers can read moissanite as diamond because both conduct heat well; a dual moissanite/diamond tester distinguishes them via electrical conductivity.
Does moissanite hold its value? Not significantly. Like most gemstones it has limited resale value; a certified lab-grown diamond retains more of a recognised market value.
Is moissanite or lab-grown more ethical? Both avoid mining. Each is created in controlled conditions with a far smaller footprint than extracting a mined stone.
