Cubic zirconia (CZ) is an artificially produced gemstone that is similar to diamond. When discussing it as a "diamond replacement", I have often seen the claim that it is inferior because it scratches more easily. For example:

Unlike diamonds, CZ’s scratch and become dull and lifeless over the long term.

Jeweler site

Cubic zirconium — Mass-produced since 1976, cubic zirconium scratches easily [...].

Business Insider - 5 ways to spot a fake diamond

Now it is true that CZ is softer than diamond (8 on the Mohs hardness scale vs 10 for diamond) - however that is still harder than most other everyday substances (Quartz has 7, glass has 5.5, steel 4-7, tungsten 7.5), so it seems unlikely to scratch in everyday use.

Is it true that CZ jewelry will scratch noticeably faster in everyday use than diamonds?

  • 5
    I wonder if other hardness 8 gemstones are similarly considered inferior because of scratching in everyday use: emerald, topaz, amethyst...
    – GEdgar
    Sep 19, 2017 at 14:43
  • @GEdgar: Good point. This could also indicate that the lower hardness is not a problem in practice.
    – sleske
    Sep 20, 2017 at 7:09
  • 2
    @GEdgar Emeralds are considered to scratch easily, and they are similar hardness. But in gemology, how easily it scratches is not only related to hardness, but also impurity. Some precious stones are more desired with impurity because they bring the color.
    – user11643
    Sep 21, 2017 at 0:47
  • @fredsbend: Sorry, I can't follow. What does scratching have to do with impurity? Or do you mean "desirability is not only related to hardness, but also impurity"?
    – sleske
    Oct 17, 2017 at 7:49
  • @sleske Impurity type and amount can affect hardness and stability of individual gems. Hardness numbers you see are averages. Desirability is a different issue and at least half subjective. General rules about desirability and value do include assessment of the impurities, but not too much on hardness.
    – user11643
    Oct 17, 2017 at 15:21


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