[lynv8]

How can I determine a true diamond? Can it be determined by its brightness with hit by a ray of light?

[The WB]

You need a diamond tester. Beware of moisanite. It tests positive with a diamond tester. Get a moisanite tester also.

[someconcerns]

How can I determine a true diamond? Can it be determined by its brightness with hit by a ray of light?

No. Diamonds, like all other gems, have characteristics like their hardness, luster, specific gravity (basically density) and refractive index. The old test of using a diamond to "cut a diamond" - the theory being that if a known diamond can cut or scratch the surface of an unknown stone, the unknown stone can't be a diamond - only resulted in a bunch of stones with scratches on them and angry people who thought they might have had a diamond.

The easiest way to tell is with a diamond tester, most often using thermal conductivity - which is in addition to the characteristics I first mentioned. The thermal conductivity tester CAN be fooled by such things as man-made real diamonds, treated diamonds (glass filling, lasers used to burn out inclusions, etc.) and moissanite.

The only sure way is to take it to a reputable gemologist who has the experience, equipment and training to tell the difference. As The WB correctly pointed out, a gemologist (or sometimes a knowledgeable jeweler) uses a combination of tests to rule out simulants. It took me years of study and practice to become a certified gemologist.

Hope this helps.

[jennycarol]

Diamond may often be mistaken for Cubic Zirconia (CZ).

True Diamonds always reflect light whereas CZ reflect different colors.

Its difficult to differentiate the two for a naked eye.