The zirconia and its differences with the Diamond

The virtue of the zirconia is at the same time its main defect. Its amazing resemblance to diamond only escapes the eyes of a good jeweler, but what about you?

a lot of zirconia

Tricks to distinguish between zirconia and diamond

If we take into account that zirconia is to date the material that best imitates diamond and that is used a lot as a gem in the jewelry industry, it is essential that we keep track of it and know some notions Basic information on its characteristics to know the differences between zirconia and diamond.


If we place a zirconia on a written paper, this gem will allow us to see the letters through it. The diamond is much more opaque and does not shine through the background on which it is placed.


Zirconia has a value of 8 on the Mohs scale (a scale used as a reference for the hardness of a substance), while diamond has a value of 10.

green and white diamonds

A diamond can scratch a zircon but never vice versa, as diamond is the hardest mineral known. So much so that special care must be taken when treating them. From JewelrySecrets we recommend that you always keep jewels containing diamonds separately, since they can scratch each other, perhaps in a bag, and separate from the others.

The heat

Diamond conducts heat very well and zirconia does not because it is much more insulating. The method most used by experts to differentiate one gem from another is the diamont tester, a detector that measures thermal conductivity.


Zirconia weighs considerably more than diamond. Being the same size, the difference is 5.40 -5.70 compared to 3.52 for the diamond. In addition to using a scale, you may notice it if you place each mineral in each hand.

The brightness

If we put a diamond in a glass of water it will continue to shine through the liquid. The zircon, however, will become almost transparent.

Our ADVICE: the best thing will always be that you go to an expert to tell you with absolute certainty if that precious stone you have or want is a diamond or a zirconia. Both are beautiful, but in addition to the price there are many other features that you have to take into account.

To learn how to look at this fascinating ‘trompe l’oeil’ like an expert, we went to the gemologist Isabel Sallent, contributor to our blog. She reveals the more technical qualities that differentiate zirconia from diamond .

Origin of zirconia (or cubic zirconia)

In principle, the name zirconia referred to the trademark of a synthetic product made as an imitation of diamond , but later it became the name of a material in Spain , which in the rest of Europe is known as djevalita.

Cubic zirconia exists in nature, it is baddeleyite in the monoclinic system. Although it has polymorphs, if it is heated it passes to the tetragonal system, and if it continues heating it melts according to some authors; or it goes to the cubic system, according to others.

rings of zirconia

Nobody tried to make a material to imitate the diamond, but the technique to obtain zirconia crystals was interested. Once they were made, they thought they could be used to synthesize diamond.

Zirconia is a material with a very high melting point:

  • Ideal for refractory material, if it were not for the fact that it transforms into its polymorphs and breaks due to its expansion, unless it stabilizes.

The first to obtain cubic zirconia were the Soviets; and then the Dilanceses. But they don’t do it the same way. That is why in commerce there are two types:

  • One that stabilizes in the cubic phase with calcium, the cheap one.
  • And another that is stabilized with yttrium, the face… And that has a higher refractive index.

In the end, all those on the market are stabilized with calcium, which is a more economical and abundant material: the two have in common that once cold they do not have polymorphs.

Cerium for oranges and reds is used to make this colored material. Chrome for green, cobalt and neodymium for blues and violets.

A fundamental characteristic of zirconia compared to diamond is that it does not present inclusions: they tend to be very clean and on few occasions we can find inclusions that can be appreciated.

When viewed, they can be small gas bubbles, solid inclusions often in rows or rows, small cloud-like areas with small particles.

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