Very high-quality forgery can only be discerned by professional gemologist (jeweler). As a rule, to the naked eye, without special tools it is almost impossible. But you can detect obvious forgery you can own, knowing a few proven techniques. To determine the authenticity of the stone you will need newspaper or any printed text on paper, a small flashlight with a bright beam of light and a container of clean water.
If the diamond you buy is not cut, then put it on the printed text and see what you can see through it. The fact that the real stone is very strongly refracts the light and you will not be able to distinguish the printed text, that is all very vague. Using fake stone letters are well mapped. Also you can check the refraction of real stone with light. Take a small flashlight and point it at the stone that the beam passed through him. If you do not see light on the other side of the stone, the diamond is likely real. Light, due to refraction, should dissipate.
Try to get some on the test stone. Since diamond conducts heat superbly, you will not be able to see it obscured the trail. But not only a diamond is capable of good thermal conductivity, so this check stone better to do with your jeweler.
Now inspect your diamond on the edge. There are natural diamonds and artificially grown. Artificial gemstones are usually much cleaner than the real thing. In the water they will be almost transparent. Real, mined from the earth, on the contrary, will have various small inclusions. But not bubbles, as the air in the stone, evidence of apparent forgery.
Despite the fact that diamonds are the hardest substance on Earth, they better not cut the glass in order to authenticate. This can significantly damage the stone.
Please note the price of the jewelry. A real gem can't be cheap.
Advice 2: As in house conditions to determine the authenticity of a diamond
Many owners of expensive jewelry turn to professionals to find out the genuine diamonds that they have. However, to answer this question by yourself. You need to do some fairly simple experiments.
One of the simplest ways to check the authenticity of a diamond lies in the definition of its reaction to moisture. Hold the diamond to your mouth and slowly exhale it. If you notice that the stone fog up for a few seconds, most likely a fake diamond. A genuine diamond has the ability to dissipate heat instantly, so blurred it is almost imperceptible. If you'll see this blurred, it disappears much faster than fake diamonds. In addition, if you repeat this experiment several times, on a real diamond, the result is always the same. Fake stone with each new approach will moisten all the more, it produces condensate.
If you check the authenticity of a diamond on jewelry, pay attention to the metal into which it is placed. Earrings, rings and other jewelry with a real diamond is likely to be made of gold, silver or other valuable metal. Armed with a magnifying glass and check the product for presence of a mark on the sample. If available, the probability that a diamond is genuine is very high. At the same time, you may find the inscription CZ (cubic Zirconia), which means that the diamond is of synthetic origin.
Real diamonds usually have an ideal composition. Look closely at it with a magnifying glass. If you see specks of extraneous minerals or small color changes, the probability that a real diamond is very high. Synthetic diamonds are grown in the laboratory, they do not have these defects, because are made in a sterile clean. However, the absence or presence of such defects can not be the determining factor. Even real diamonds can be perfectly clean. Be sure to conduct additional research.
If you have a fairly large stone, you can determine its authenticity by checking its refraction. Pick up a newspaper and look at it through the diamond. If you will be able to read printed text, or at least see him with the big distortions, to be sure, this is a fake diamond. Genuine diamond very strongly refracts the light, so to see anything specific for him is almost impossible, unless prepared in a special way.
Real diamond is a very hard material, it is quite difficult to break. Heat the stone using a small fire for 30 to 40 seconds, then quickly dip it in a glass of cold water. If the stone is made of glass or quartz, it is quickly covered with cracks.