Cubic Zirconia VS. Diamond

2017-05-10 ONEGEMSTONE 2009

Although very different in other properties, cubic zirconia and diamond appear similar to a lay person because of their outer appearance and high refractive index. Fact is, diamond is a very expensive, naturally occurring substance, whereas Cubic Zirconia is manufactured and a less expensive jewelry substitute for diamonds.


Cubic Zirconia



Since CZ are synthetic, they can be made absolutely colorless.

Diamonds usually have a yellow or brown tinge,

 the truly colorless diamonds are very rare.


CZ, the cubic crystalline form of zirconium dioxide(ZrO2), 

is a mineral that a widely synthesized for use as a diamond simulant.

Diamond is a natural mineral, an allotrope of carbon.

Crystal Habit

Dipyramidal prismatic

Isometric, Octahedral

Crystal System

Tetragonal; 4/m 2/m

Hexoctahedral (cubic)


Mainly as a gemstone, as it bears high similarity to diamond.

Jewelry; industrial purposes, high-pressure experiments, 

cutting tools.








Relatively hard, though nowhere near diamond but harder than 

most of natural gemstones found. 8.5 on Mohs hardness scale.

Extremely hard (10 Mohs scale). 

The hardest known natural material.

Specific Gravity

The specific gravity of CZ is between 5.6 to 6 and 

is relatively 1.7 times more than that of a diamond of the same size

Diamond has a specific gravity of 3.52

Refractive Index



Chemical formula




0.060 (higher than diamond)

0.044 (lower than cubic zirconium and moissante) 




Thermal conductivity

CZ are thermal insulators

Diamonds are among the most efficient thermal conductors.


Production of cubic zirconia is virtually flawless.

Diamonds definitely have some kind of flaw.

Melting Point

2750 ℃ (4976 ℉)

3550 ℃ (6422 ℉)


In CZ, the shape of the facet is sometimes different from that of

a diamond

Diamonds can be of various cuts.


Diamond is and allotrope of cabon. It is the hardest known natural substance. Its hardness and high dispersion of light make it useful for industrial applications and jewelry. Diamonds make excellent abrasives because they can be scratched only by other diamonds. Because all these qualities and its rare natural occurence, the cost of diamonds is very high.

To substitute expensive diamonds in jewelry, a cheaper alternative was found to be cubic zirconia as a common name would call it. CZ is the cubic crystalline form of zirconium dioxide(ZrO2), is a mineral that is widely synthesized for use as a diamond simulant. The synthesized material is hard, optically flawless and usually colorless, but may be made in a variety of different colors. It has close visual likeness to diamond and is relatively cheaper.


Diamond is the hardest natural material known to man, it measures up to a perfect 10 on the Mohs' hardness scale. They are good abrasives and can be scratched only by other diamonds. This quality is useful in its use as jewelry. Industrial use of diamonds has historically also been associated with their hardness, it can be used to polish, cut, or wear away any material, including other diamonds. Cubic Zirconia are also relatively hard as compared to other gemstones though its hardness cannot measure anywhere close to diamonds. On the Moh's scale it is 8.5.

Electrical and Thermal Conductivity

Diamonds are electric insulators and excellent thermal conductors. Cubic Zirconia are thermal insulators.


Diamonds are generally found with a yellow pr brown tinge in them, this is due to the nitrogen found in them. The color depends on the concentration of nitrogen or other such subsitutes in the diamond. The really colorless diamonds are the ones which are free of any flaws and usually rare. Cubic Zirconia on the other hand being a synthesized product, can be made absolutely colorless. It can be given the grade "D" which is the best quality diamond on the diamonds color grading scale.


Dispersion of Cubic Zirconia is higher than diamond making the prismatic fire more intense in it. Diamond dispersion is 0.044 while CZ is 0.060.

Specific Gravity

Cubic Zirconia crystals are heavyweights in comparison to diamonds; a Cubic Zirconia will weight about 1.7 times more than a diamond of equivalent size.

Refractive Index

The refractive index of cubic zirconia is lower than that of a diamond. It has a refractive index of 2.176, compared to a diamond's 2.417.


All diamonds have some kind of defect, it can be a feather, an included crystal or a remnant of an original crystal face (e.g. trigons). Cubic Zirconia on the other hand are synthetic and hance are virtually flawless.


Diamonds are a natural material and are thought to have been first recognized and mined in India (Golconda being one of the first places), where significant alluvial deposits of the stone could then be found along the rivers Penner, Krishna and Godavari. n the twentieth century, experts in the field of gemology have developed methods of grading diamonds and other gemstones based on the characteristics most important to their value as a gem. Four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds: these are carat. cut, color and clarity.

Cubic Zirconia is not a natural material but is a synthesized form of zirconium oxide which was extracted from the mineral baddeleyite. It has diamond look alike properties.

Formation and Manufacturing

The formation of natural diamond requires very specific conditions. Diamond formation requires exposure of carbon-bearing materials to high pressure, ranging approximately between 45 and 60 kilobars, but at a comparatively low temperature range between approximately 1652-2372 ℉ (900-1300℃). The depths of craters in which diamonds are formed are estimated to be in between 140-190kilometers (90-120 miles) though sometimes is can be much more than this too. Long residence in the cratonic lithosphere allows diamond crystals to grow larger.

Cubic Zirconia on the other hand is man made product. Baddeleyite was discovered in 1892, the yellowish monoclinic mineral baddeleyite is a natural form of zirconium oxide. In 1930, stabilized zirconia was obtained after stabilization of zirconium oxide had been realized. Seven years later, German mineralogists discovered naturally occurring cubic zirconia in the form of microscopic grains included in metamict zircon. Ad with the majority of grown diamond look-alikes, the conceptual birth of single-crystal cubic zirconia began in the minds of scientists but it was later in 1960s in France when research into controlled single-crystal growth of cubic zirconia occurred. The Soviets later perfected the method and called it skull crucible and named the jewel, fianit, though the name was not used world wide. Their breakthrough was published in 1973, and commercial production began in 1976.By 1980 annual global production had reached 50 million carats(10000kg). The method is still used today with some variation.


Wikipedia: Cubic Zirconia

Wikipedia: Diamond

TAG:   cubic zirconia diamond

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