Anyone can be fooled by imitations, even diamond experts. However, by doing the following tests, you can reduce your chances of being fooled.
See-through Test Look at the stone face up. Can you see through it? If you can, it's probably an imitation (In some cases a poor cut or the presence of dirt or grease makes it possible to see through a diamond). The seat through test can also be done by placing a clean, round stone face down on newsprint. If you can see the letters through the stone, it probably is an imitation. For fancy shapes such as ovals and pears, it's best to limit this test to the face-up view because often, you can see through their pavilions.
If you plan to examine stones in antique jewelry, you should be aware that the diamonds may have a see-through effect due to the different cut and the large culet. Tilt Test Tilt the stone against a dark background. Can you see an obvious, dark, fan-shaped area If you can, it's doubtful that it is a diamond. This test is a variation of the see-through test, but it's easier to do on mounted stones. It also works best on round diamonds.
Rainbow Colors Test Move the stone under a light and note how strong the flashes of rainbow colors are in comparison to a diamond under the same light. If the rainbow colors (also called dispersion or fire) are a lot more obvious than your diamond, the stone may be synthetic retile or strontium titan ate. If they're less obvious, the stone may be an imitation or a diamond with a large table and a thin crown. This test is most useful for distinguishing diamond from synthetic retile and strontium titan ate, the two imitations which, like diamond, can be cut to have no see-through effect.
CZ (cubic zirconium) also displays more rainbow colors than diamond, but sometimes it's hard for the untrained eye to see the difference. It's particularly important to compare CZ and diamond under the same light. The rainbow colors are easier to see in sunlight and under incandescent light (from light bulbs) than under fluorescent light.
