If you desire to invest in diamonds, it is important that you get a genuine diamond for your hard money spent. There are jewelers, who might sell cubic zirconia in place of diamonds. Thus, you must know the tests employed for differentiating diamonds from cubic zirconia, so that you have good reason to wear your rings, earnings, necklaces and other diamond jewelries proudly.

Traditional Scratch Test
It has been believed that only diamonds can scratch glass surfaces, but studies have proved that even cubic zirconia can produce such results. On top of that, you might damage the surface of your diamonds, leading to degradation of its looks, while performing this test.
Transparency Test For Diamonds
It is a well known fact that diamonds don’t allow to clearly read writings through them. It is the test, which is good only for loose diamonds. Moreover, the diamonds with thin cuts are capable of allowing the tester to read through them. Thus, this test is not completely reliable for evaluating the worth of a diamond.
A Similar Fog Test
As we know, diamonds are not capable of holding heat; you can test its authenticity by breathing upon it just like we do on a mirror. If the diamond retains a foggy appearance for few minutes, it is a fake piece. For achieving accurate results, make sure that the jewelry piece is cleaned by following various techniques of diamond cleaning.
Weight Test With Similar Cubic Zirconia
You can tell whether your possession is a real diamond or not, by testing it with a weighing machine. You can purchase a cubic zirconia with same size and weight from the market and use it to be weighed with product in your possession. The fact that a cubic zirconia weighs lore than a diamond can help you to arrive at conclusion.
Ultra Violet Test
You can apply UV rays on your diamond jewelry and test against various fluorescent effects produced. It is known that cubic zirconia exhibits different fluorescent results. Also, you can test diamonds with a black light, as a genuine diamond will always emit deep blue light in this test.

Loop Test
View the piece of jewelry under a magnifying glass and analyze the facet joints and girdles. A real diamond will always possess frosty girdles and not the waxy ones. You can also search for C.Z. engraved on your jewelry to tell whether it is real diamond or fake.
Before you believe any of these tests, it is necessary to consult and expert, who can easily guide you in this direction.