It's easy to be fooled by imitation diamonds also known as stimulants.
Four Major Stimulants
Synthetic rutile, strontium titanate, and synthetic moissanite (i.e., silicon carbide) can be cut in the same fashion as a diamond which makes it easier for these imitations to pass the see-through test. Synthetic moissanite is the highest priced imitation diamond on the market which usually sells for several hundred dollars per carat. Plus, it can easily pass the thermal conduction test.
Here are some tests you can do to determine if the diamond that you intend to purchase or have already purchased is a real diamond or an imitation.
See-Through Test- With this test, you should examine your diamond face-up. Make sure that your diamond is clean before conducting this test. It's best that you lay your diamond on a sheet of newsprint. If you can see the letters through the diamond, then your diamond is clearly a fake. Essentially, if you can see through your diamond as if you were looking through glass, then you have an imitation diamond in your possession.
Tilt Test- With this test, you must tilt your diamond against a dark background. If you're able to see a dark fan shape inside of the diamond, then your diamond is an imitation. This test works best with round shaped diamonds.
Rainbow Colors Test- First, make sure that you are examining your diamond under sunlight or incandescent light. Move your stone under the light and pay close attention to how strong the rainbow colors (also known as dispersion or fire) are in comparison to a known diamond. If the rainbow colors are very obvious, then your diamond is an imitation. Cubic Zirconia displays more rainbow colors than diamonds. Your imitation diamond may be made of synthetic rutile, strontium titanate, or synthetic moissanite. This test is very effective at detecting if a diamond is one of these three common imitation diamonds.
Closed-Back Test- When purchasing jewelry, you should check to see if your diamond's pavilion is showing through the back side of the setting. If not, this might be an indication that your jeweler is hiding something. It could be that the stone is a rhinestone, or that the diamond is coated in some material to enhance its color. Always try to buy a diamond that is in a setting where at least a small part of the pavilion is showing to prove that your diamond is indeed a real diamond.
Price Test- If your diamond is being sold for an unbelievably low price, then your diamond is most likely an imitation or a stolen piece of merchandise. Diamonds are very expensive commodities and a jeweler can't make a real profit if they are selling diamonds at prices below the market price.
Thermal Conduction Test- To conduct this test, you must purchase the GIA GEM pocket thermal tester which allows you to measure the heat conductivity of a stone. This instrument contains a metal probe (i.e., heat pen) which presses against the facet of the stone. There's a needle on the instrument which then notifies you if you're diamond is an imitation or a real diamond. Synthetic rutile can easily be detected under this test. Since synthetic moissanite can react similar to a diamond under this test, it's best to also conduct a doubled facet test, and to analyze the specific gravity and reflectivity of the stone in order to know for sure if your diamond is real or fake. You can also use a moissanite tester to see if your diamond is indeed a moissanite. The thermal tester used for this test can be purchased from the GIA Gem Instruments Corporation in Carlsbad, California.
Girdle Test- Using a 10-power magnifier, carefully examine the girdle around your diamond. If it has been carefully formed, then it's a real diamond. In some cases, real diamonds may have naturals in their girdle. A natural is a portion of the original surface of the diamond. The presence of naturals can make it easier to identify your diamond as being a real diamond versus a fake one. Sometimes imitation diamonds have formations along their girdles that appear similar to naturals so be careful. If the formations on the girdle appear to be rounded, then the diamond is an imitation. Real diamonds have angular formations, step-like ridges, lines, or trigons (triangular indented growth marks) on their girdles.
Doubled Facet Test- With this test, you will be able to detect if your diamond has a doubling effect. If you see doubled facets or a table reflection when you look at the stone through a magnifier, then there is a great chance that your diamond is an imitation. Imitations tend to refract light in two directions while real diamonds refract light in one direction and their facets appear as single lines. To conduct this test, you need to tilt the stone and look at it from an angle. If you're looking at the diamond under a defocused microscope or focusing on a point past the culet of the diamond, it will also make it easier to detect doubling. Synthetic rutile and synthetic moissanite display doubling which makes this an excellent test for either one of these imitations.
Glass Test- To determine if your diamond is an imitation, you should use a loupe and examine your stone very carefully. If you notice any gas bubbles inside of the stone, then it's clearly a fake diamond. Gas bubbles are usually round, oval, elongated or donut shaped. These bubbles are sometimes visible with the naked eye. Other characteristics of glass that you should be looking for:
- Rounded facet edges (in comparison, real diamonds have sharp facet edges)
- Concave facets and surfaces
- Swirly lines or formations
- Uneven or pitted surfaces
Imitations tend to have gas bubbles and appear flawless. Real diamonds may have diamond crystals (as well as other inclusions and blemishes), distinctive graining, laser drill holes, naturals & trigons. You should be able to initially spot a fake diamond after conducting this test.
- You can examine the transparency of your stone. Diamonds tend to have a high transparency. If your stone appears hazy or cloudy, then you may have an imitation such as cubic zirconia. It's important to note that some diamonds may be cloudy or hazy so further tests must be conducted to rule out your stone as an imitation.
- To determine if your stone is real or fake, you can measure the reflective capacity of your stone using a reflectometer. Make sure that your stone is clean and polished before using this device.
- You can compare your stone's weight to the weight of a diamond with the same size. Diamonds have a lower specific gravity than most imitations. In other words, a diamond will sink slower in heavy liquids in comparison to most stimulants. Synthetic moissanite has a lower specific gravity than diamonds, so in order to distinguish a synthetic moissanite from a diamond is to place your stone in methylene iodide. If your stone floats, then it's a synthetic moissanite. If it sinks, then it's a diamond. Note: Methylene iodide is very toxic and should only be handled by a trained professional or lab technician in a very well ventilated room.
- If you x-ray your stone, you can also determine if your stone is fake or real. Diamonds are transparent to x-rays while imitations are not. Diamonds also fluoresce blue when exposed to x-rays.
- You can use a spectroscope to measure how your stone absorbs light. Diamonds have a characteristic reading and this test will allow you to determine if your stone is an imitation or not.
- You can place your stone under short-wave and long-wave ultraviolet light, then compare its fluorescence to a real diamond.