Cubic zirconia: what it is and how it differs from diamond

Cubic zirconia is a clear stone that sparkles almost like a diamond but costs a small fraction of the price. Here's what it really is, how it differs from diamond and from natural zircon, and how to look after it so it keeps its sparkle.

What is cubic zirconia?

Cubic zirconia – often shortened to CZ – is a crystal grown in a laboratory, created specifically as an alternative to diamond. It's hard (around 8 on the Mohs scale), completely transparent and strongly refracts light, so it doesn't lose its sparkle.

Cubic zirconia, zircon and diamond: three different things

The names sound alike and are constantly mixed up:

• Cubic zirconia (CZ) – a lab-created stone and the one you'll see most often in fashion jewellery. It's the subject of this article.
• Zircon – a natural mineral formed deep in the earth. A different material at a different price.
• Diamond – a natural crystal of carbon, the hardest of the three (10 on the Mohs scale) and the most expensive.

How cubic zirconia differs from diamond

• Sparkle. Cubic zirconia throws out more flashes of colour – what jewellers call ‘fire’; a diamond's sparkle is whiter and more restrained.
• Hardness. Diamond is the hardest natural material; over the years cubic zirconia can pick up tiny scratches along its facet edges.
• Weight. A cubic zirconia is heavier than a diamond of the same size.
• Price. Here the difference can be a hundredfold – which is exactly why cubic zirconia is so common in everyday jewellery.

How to tell them apart

At home there are two things you can reliably check: cubic zirconia is heavier, and it holds warmth for longer once you've held it between your fingers, whereas a diamond draws heat away almost instantly. Only a jeweller with the right instrument can give you a definitive answer – but an honest seller states the material in the product description, and then no test is needed.

How to keep the sparkle

Cubic zirconia doesn't lose its brilliance because it wears out, but because a greasy film from creams and skin builds up on it.

• Every couple of weeks, rinse the stone in warm water with a drop of soap and dry it with a soft cloth.
• Put your jewellery on after moisturiser and perfume.
• Store pieces separately – a hard stone will scratch softer neighbours in your jewellery box.

The rest of the care basics are gathered on our jewellery care page. You can browse pieces set with cubic zirconia in our collection of jewellery with stones.

Frequently asked questions