What is cubic zirconia?

If you have seen “cubic zirconia” in the description of a ring and did not know whether that was good news or bad, the answer is that it is neither: it is a material with a name of its own, declared because it has a name of its own. What follows is what it is, how it differs from a diamond and what to expect from it with wear.

What it is, exactly

Cubic zirconia is zirconium oxide crystallised in its cubic form. Hence the two long names, which mean the same thing: cubic zirconia and cubic zirconium oxide. It is made in a furnace, melting the oxide at more than 2,500 °C with a stabiliser that forces it to crystallise into cubes instead of into its natural form.

Zirconium oxide does exist in nature — it is called baddeleyite — but practically never in cubic form and never in sizes that are any use for jewellery. So all the cubic zirconia on the market is lab-grown, and that is not a flaw anyone is hiding: it is its definition. It went into mass production in the mid-1970s, precisely in order to have a clear, very bright stone at a low cost.

Cubic zirconia and diamond: the real differences

Both are clear and both sparkle, and from a metre away they look alike. These are the differences you can measure:

There is one confusion worth clearing up: a lab-grown diamond is not a cubic zirconia and not an imitation. It is diamond, with the same composition and the same hardness as the mined one; the only thing that changes is where it formed. Cubic zirconia is a different material altogether.

How to tell them apart without instruments

• The weight. At the same size, cubic zirconia weighs around 60% more than a diamond. It is the most reliable test you can do by hand: if a large stone feels light, it is not cubic zirconia.
• The colour of the flashes. Cubic zirconia scatters light more, so it throws back more coloured sparks; a diamond throws back more white light. Side by side, that extra “rainbow” shows.
• The scratches. A cubic zirconia that is years old has micro-scratches on its edges and on its top facet, which is why it loses clarity. A diamond does not.

What it costs

This is the stone’s whole reason for existing. A one-carat diamond is counted in thousands of euros; rough cubic zirconia sells for cents per carat. In a finished piece, what you pay for is the design, the metal and the work of setting it, not the stone. That is why a ring with cubic zirconia can cost twenty euros or a thousand, and in the second case the expensive part is not the cubic zirconia.

The practical consequence: if a shop charges you a premium for the stone, presenting it as something exceptional, the premium is not in the material.

Is selling cubic zirconia a con?

No, as long as it is stated. It is a stone with a name, with centuries less history than the diamond but with an identity of its own, and millions of people wear it every day precisely because losing it is not frightening.

What is a con — and in Spain is an unfair commercial practice — is selling it as a diamond, calling it a “synthetic diamond” or leaving the material undeclared so that the buyer assumes. The question that settles the matter in one line is “which stone is in it?”. If there is no clear answer, you already have one.

How to look after it

Cubic zirconia does not tarnish — it is an oxide, it is already oxidised — but it does go dull, for two reasons: the grease from your skin and micro-scratches. The grease comes off; the scratches do not.

• Warm water with a drop of mild soap, your fingers, rinse and dry. The detail is in how to clean jewellery at home.
• Never an ultrasonic cleaner on a piece where the stone is glued rather than claw-set: the vibration lifts it off.
• Store it where it cannot rub against other pieces. One cubic zirconia scratches another, and both lose.

What Aver Jewels pieces are made of

Our catalogue sets cubic zirconia and enamel on bronze with 24 kt gold plating. We say so on every product page and we repeat it here because it is the information that makes a price of between €22 and €72 make sense: there is no solid gold, there are no diamonds and there are no precious stones. There is design, work done by hand and materials that are declared.

Some older pieces in the catalogue do carry a natural stone — agate, amethyst, amber, onyx — and their product pages say so. If you want the detail on the metal and the plating, it is in gold plating explained.