Cubic zirconia is a laboratory-made gemstone that gives the bright, colourful sparkle of a well-cut diamond at a fraction of the price. It is not a diamond, and it is not trying to be one when it is described honestly. This guide explains what cubic zirconia is, how it compares with diamond, and how to keep it looking its best.
What is cubic zirconia?
Cubic zirconia, often shortened to CZ, is a crystal of zirconium dioxide. It is made in a laboratory and does not occur naturally in jewellery-quality form. Its name comes from its cubic crystal structure, the same symmetrical arrangement that gives diamond its brilliance.
A well-cut cubic zirconia is clear, bright and almost always free of the inclusions found in many natural stones. That consistency is a large part of its appeal. Every stone in a pair of earrings or a line of claw-set stones can be matched closely in colour, size and sparkle.
How cubic zirconia is made
Cubic zirconia has been produced commercially since the 1970s. Most is made by a method known as skull melting. Zirconium oxide powder is mixed with a small amount of a stabilising oxide and heated to around 2,750°C.
The outer layer of powder stays cooler and forms a solid crust, or “skull”, which holds the molten material inside. As it cools slowly over several hours, large clear crystals grow. These are then cut and polished in the same way as other gemstones, using the facet patterns familiar from diamond.
Cubic zirconia compared with diamond
Cubic zirconia and diamond look similar at a glance, but they are different materials with different properties.
| Cubic zirconia | Diamond | |
|---|---|---|
| Material | Zirconium dioxide, laboratory-made | Carbon, natural or lab-grown |
| Hardness (Mohs scale) | 8–8.5 | 10 |
| Brilliance (refractive index) | About 2.15–2.18 | About 2.42 |
| Fire (rainbow flashes) | Stronger | Softer, more white light |
| Weight for the same size | About 1.7 times heavier | Lighter |
| Clarity | Almost always flawless | Varies from stone to stone |
| Price | A small fraction of diamond | Considerably higher |
Sparkle. Cubic zirconia shows more fire than diamond: more of the coloured flashes you see as a stone moves. Diamond returns more white brilliance. Many people find cubic zirconia slightly livelier, while a trained eye notices the difference.
Hardness. At 8–8.5 on the Mohs scale, cubic zirconia is harder than most gemstones and wears well. Diamond, at 10, is harder still, so over many years a cubic zirconia may show fine wear on its facet edges.
Size and carat. Because cubic zirconia is denser, a stone the same size as a one-carat diamond weighs more. For that reason it is usually described by its measurement in millimetres rather than by carat.
Colours, cuts and quality
Most cubic zirconia is colourless, but it can be made in almost any colour by adding small amounts of other elements during growth. Pink, blue, green, purple and yellow stones are all common. Coloured cubic zirconia offers a bright, even colour that is hard to find in natural gemstones at the same price.
Cubic zirconia is cut in every popular shape: round brilliant, princess, oval, pear, emerald, cushion and heart. As with diamond, the cut matters most. A precisely cut stone with well-proportioned facets returns more light and looks noticeably livelier than a poorly cut one.
Quality also shows in the setting. Secure claws, a neat finish and stones that sit level are signs of a well-made piece.
Cubic zirconia in gold and silver
Cubic zirconia is set in both 9ct gold and sterling silver. In gold, it gives the look of a diamond-set design at a far more accessible price, while the metal itself remains genuine, hallmarked precious metal. In sterling silver, it is the natural partner for everyday fashion jewellery.
When you buy cubic zirconia jewellery, most of its lasting value is in the metal and the craftsmanship. The stones are chosen for beauty and wearability rather than as an investment.
How we describe cubic zirconia
At Malcolm Cooper Jewellery, every piece set with cubic zirconia says so clearly, in full, in its title and description. We never describe cubic zirconia as diamond, and we do not use vague phrases that could suggest it is something it is not.
Cubic zirconia is also different from the other stones it is sometimes confused with:
- Lab-grown diamond is real diamond, made of carbon, with the same properties as a natural diamond.
- Moissanite is silicon carbide, a different laboratory-made gemstone that is harder than cubic zirconia.
- Cubic zirconia is zirconium dioxide: beautiful and durable, but neither diamond nor moissanite.
Knowing the difference means you can choose with confidence and know exactly what you are paying for.
Caring for cubic zirconia jewellery
Cubic zirconia attracts skin oils, soap and lotion, which dull its sparkle. A little regular care keeps it bright.
- Clean gently. Soak in warm water with a drop of mild washing-up liquid, brush lightly with a soft toothbrush, rinse and dry with a lint-free cloth.
- Avoid harsh chemicals. Keep pieces away from bleach, chlorine and household cleaners, which can harm both stones and metal.
- Store separately. Keep each piece in its own pouch or compartment. Cubic zirconia can scratch softer gems and metal, and harder stones can scratch it.
- Put jewellery on last. Add it after perfume, hairspray and cosmetics, and take rings off for gardening, cleaning or the gym.
- Check the setting. Every so often, look at the claws or rubover settings to make sure every stone is secure.
Beautiful sparkle, honestly described
Cubic zirconia offers bright, lasting sparkle in gold and silver at a price that leaves room for more than one favourite piece. Chosen for what it is, it is a beautiful and practical choice for everyday and occasion jewellery.
Browse cubic zirconia pieces in our Earrings, Dress Rings, Neckwear and Bracelets collections. If you are considering a diamond instead, our Diamond Guide explains the choices.