How to Tell the Difference Between Diamonds & Cubic Zirconia

Increasingly, environmentally conscious consumers are turning to cubic zirconia as a substitute for diamonds. The synthetic gemstone also costs a fraction of what you would pay for a diamond ring. A tool like a jeweler's loupe needs to be used to determine if a stone is a diamond or a cubic zirconia (CZ) because a lot of people, including trained gemologists, can't tell the difference with their naked eye.

Lack of Color

Cubic zirconia can be manufactured to be completely colorless. Only extremely rare diamonds are totally colorless; most have a brown or yellow tinge.

Heat Conductivity

Diamonds are good thermal conductors, which means heat easily passes through them, but cubic zirconias act as insulators and will reduce the rate of heat transfer.

Flaws

Diamonds tend to have impurities or defects, like a feather (an area that blocks the light), whereas man-made cubic zirconia are essentially flawless.

Weight

A CZ weights about 1.75 times more than a diamond of the same size; if you had a cubic zirconia that was the size of a two-carat diamond, the CZ would weigh about 3.5 carats.

Hardness

Diamonds have a 10 rating on the Mohs hardness scale. Cubic zirconia rate 8.5 to 8.9.

Refraction Index

A cubic zirconia's refractive index is 2.176, but a diamond's is 2.417.

Fire

Diamonds have much less fire than cubic zirconia, which flash only orange. Diamonds will flash orange and blue.

Resources

• Penny CZ Jewelry