Geology Home Page physical geology historical geology planetary gems
Roger Weller, geology instructor
by Martha Thompson
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)
Picture courtesy of Myweddingideas.net
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.
Picture courtesy of almost diamonds.com
Because of it’s low cost , durability , and close visual likeness to diamonds , cubic zirconia is sometimes marketed under it’s brand name “Diamonique”.
Pictures courtesy of allmostdiamonds.com
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.
Red , orange, yellow
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.