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Roger Weller, geology instructor

cubic zirconia
by Martha Thompson
Physical Geology
Fall 2010



                                                                  Cubic Zirconia
          Cubic Zirconia is well known as a substitute  for diamonds, due to its  high  hardness and great  fire.  CZ is a beautiful synthetic gemstone that is durable and inexpensive and now comes in  any color of the rainbow, making it more desirable.  Cubic zirconia is a  form of zirconium oxide that is created in a laboratory, However it was found to be naturally occurring  once at one site  in the 1930’s, but has yet to be discovered since then. (Nassan, 1981)


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          Cubic Zirconia has a hardness of 8.5 on Mohl’s scale of hardness  and a white streak. It has a specific gravity between 5.65 and 5.95 and a density between 5.5 and 5.9 .  Since cubic zirconia is transparent, it Is  often faceted.  It can be made in nearly any color and can be faceted into many cuts.

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          Because of it’s  low cost , durability , and close  visual  likeness to diamonds , cubic zirconia is sometimes marketed under it’s brand name “Diamonique”.





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         In recent years manufacturers have sought ways of distinguishing their product by  improving cubic zirconia, by coating  it with a chemical vapor deposition. The  resulting material is made harder more lustrous and more like diamond.   




          Colored cubic zirconia is produced by using  different oxides to achieve  colors.




Colors produced

Cerium  oxide

Red , orange, yellow

Copper oxide

Yellow , amber,  brown



          To the untrained eye, cubic zirconia looks identical to a good quality diamond, but CZ has  less brilliance and lacks the sparkle of a real diamond.  The effect can sometimes often fool  a trained gemologist.  A piece of CZ  is about  75% heavier than a real diamond.  A piece of CZ  the same size as a  one carat diamond weighs about 1.75 carats. Cubic zirconia is also flawless  whereas diamond usually contains impurities and inclusions.           




          Cubic zirconia has many advantages  one being the obvious is the price difference as compared to a diamond. Hardness denotes resistance to scratching as opposed to toughness which relates to  the ability to resist  breakage from falls  or impacts.  The disadvantages to cubic zirconia are not good investments , do not

Hold their price. Cubic zirconia has less sparkle than diamonds .The white color of the cubic zirconia is a less believable imitation as white-white color diamonds  are extremely rare. Cubic zirconia is not rare and can be made quickly and in vast quantities , whereas  natural diamonds take years to form. Cubic zirconia has not yet got  the same status as a diamond and  does not indicate wealth.









Works Cited