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Why is Cubic Zirconium used as a Diamond substitute?
| Submitted by: | Anon |
| Date: | 2004-03-21 |
| Answered By: | Jon Hill (University of Edinburgh) |
Cubic Zirconium (CZ) is a manufactured mineral, introduced in the gem market in 1976. Comparing the properties of diamond and CZ, it is easy to see why it is a popular diamond substitute. Quartz is also in the table for comparison.
| Mineral | Refractive Index | Dispersion | Isotropic or Anisotropic |
Specific Gravity (SG) | Hardness |
| Diamond | 2.42 | 0.044 | I | 3.52 | 10 |
| CZ | 2.16 | 0.06 | I | 5.9 | 8 |
| Quartz | 1.55 | 0.013 | A | 2.65 | 7 |
As you can see CZ has a high hardness, takes a good polish and resists scratching. The high refractive index produces a brilliance approaching that of diamond. The dispersion is high, but not excessive.
Other minerals that are used as gem substitutes are manufactured garnet as a substitute for diamond. Garnet can look like ruby (corundum), however the most common mistake is made with pyrite - otherwise known as Fools Gold. Gold and pyrite are easy to tell apart however. Gold is softer (2.5 compared to 6), denser (SG=19.3 compared to SG=5) and a gold-yellow streak compared to a black/green-black streak for pyrite.
Come and discuss this and other topics in the forums.
References
C. Klein and C.S. Hurlbut, Jr., 1993. Manual of Mineralogy (21st Edition).
W.R Hamilton, A.R. Wooley and A.C. Bishop, 1992. Minerals, Rocks and Fossils.
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