Many people like to be able to check their own jewelry to see if their diamond is real. There are a few things that you can do yourself to help determine a diamond's authenticity, however, to a get a true verification you should take your jewelry to a qualified jeweler or gemologist and allow them to test your diamonds.
One of the easiest do it yourself tests to help determine if the diamond you have is real of a CZ is the dot test. Since diamonds reflect light back out through the table (top surface) and CZs are transparent, you can perform a visual test.
|The Dot||The dot through a CZ||The dot through a diamond|
One concern that many people have is when they see their diamond "glow" when under a black light or in a bar. Some people claim that this means the diamond is real, while others claim that this means the diamond is fake. Neither is the case all of the time. Real diamonds can glow under black light, or ultra violet light, this is called fluorescence.
Fluorescence is a characteristic of natural diamonds that is measured and declared on all major lab reports. Fluorescence can vary in intensity from not at all visible or very strong where the diamond simply glows bight colors. This is not a defect, and it in no way affects the value of your diamond, it is simply a property of your diamond. Many people seek out these types of diamonds especially for this feature.
Many gemstones can scratch glass. Glass has an average hardness of 5.5 on the Mohs' scale for hardness. A diamond has a hardness of 10. A CZ has a hardness of 8.5. Other gemstones harder than glass include Sapphire, Amethyst, Quartz, Aquamarine Ruby and Emerald.
By trying to scratch a piece of glass with you gemstone as a test, all you are doing is scratching glass and risking damage to your gemstones. This is not a good test to determine if your diamonds are real.