A cubic zirconia is not a synthetic diamond but it is a simulant. Simulants are stones that are made to physically look like a certain stone but isn't in composition, structure or form. Cubic zirconia's chemical composition, atomic structure, make-up. etc. is completely different from that of diamond. Cubic zirconia is so optically close to diamond that only a trained eye can easily differentiate the two. Following are the key features of cubic zirconia which distinguish it from diamond:

1. Dispersion: With a dispersive power greater than diamond the more prismatic fire of cubic zirconia can be seen by even an untrained eye.

2. Hardness, Cubic zirconia has an 8.5 to 8.9 on the Mohs' hardness scale vs. a rating of 10 for diamonds meaninf diamonds are harder than cubic zircona.

3. Flaws: Contemporary production of cubic zirconia is virtually flawless, whereas most diamonds have some sort of defect, be it a feather, included crystal, or perhaps a remnant of an original crystal face (e.g. trigons). Most natural diamonds have some sort of inclusion in them some you can see with the naked eye, other inclusions you can see with a loop.

4. Specific gravity: Cubic zirconia crystals are heavyweights in comparison to diamonds. Cubic zirconia is heavier than a natural diamond, about 1.5 times heavier.

5. Refractive index: Cubic zirconia has a refractive index of 2.176, compared to a diamond's 2.417. CZs have substantially more fire than diamonds, and the flashes you get from the pavilion when you rock the gem, will be orange, while with diamonds they will be orange and blue. A diamond always more gives more "sparkle" than a cubic zircona.

6. Color: Only the rarest of diamonds are truly colorless, most having a tinge of yellow or brown to some extent. By comparison, cubic zirconia can be made in most cases entirely colorless: equivalent to a perfect "D" on diamond's color grading scale.

7. Cut: Under close inspection with a loupe, the facet shapes of some cubic zirconias appear different from diamonds. Polish marks on diamonds run per facet in different directions, while on CZ they usually run all in same direction.

8. Thermal conductivity: Cubic zirconias are thermal insulators while diamonds are among the most efficient thermal conductors, exceeding copper.

9. When you put a CZ and a diamond on paper with text, with the table on the paper, you will see that a well cut diamond does not make you see any of the text below, while the CZ a little bit.

10. Affordability: Cubic zirconia are so much more affordable than a naturally mined diamond. Diamonds are overpriced and overhyped by DeBeers and the diamond industry.

This information will help one to know the difference between diamond and cubic zirconia.