Check your diamond's authenticity at home.

How to Test Your Diamond Stone To See If It is Real

by Melissa King

For many, a diamond's glittering beauty is the symbol of purity and love. Real diamonds have a hefty price tag, so jewelry stores often sell man-made gems for customers who want a more affordable option. To the untrained eye, these fakes look just like the real thing. You don't need to take your stone to a jeweler to test its authenticity, though. You can verify the gem yourself with a few basic at-home tests.

1. Transparency Test

To perform the transparency test, lay a sheet of newspaper on a flat, well-lit surface, such as a desk or table. Set the diamond on the newspaper with the flat side facing down. Try to read the newsprint through the diamond. If you can clearly read the print, the diamond is probably fake. Some very shallow-cut diamonds may fail this test. If your diamond is low-cut, try a different test.

2. Magnifying Glass Test

In a well-lit room, hold your diamond in one hand and a magnifying glass in the other. Inspect the diamond carefully. Look for tiny imperfections, such as nicks or small cracks. Real diamonds have these; fakes usually don't. A real diamond may have a frosty appearance. If the diamond looks slick or waxy, it's fake. A real diamond has sharp-edged facets. The facets of a fake diamond may look blunt or rolled. Examine the setting for a stamp, such as "14K." If you see a stamp, the setting is likely real gold or platinum, so the diamond is probably real as well. If you see the stamp "C.Z.," the stone is a cubic zirconia, not a diamond.

3. UV and Fog Test

Hold your diamond under a black light or UV light and look for color changes. Real diamonds typically glow blue when held under a black light; most fakes won't glow at all. Some very high-quality diamonds may not glow blue, however. For the fog test, hold your diamond in front of your mouth and breathe on it. If the diamond is real, the fog on it should dissipate instantly. If it's fake, the fog will remain on the stone for two to four seconds. This test may fail if the top of your stone is a diamond glued onto a cubic zirconia base.

4. Weight Test

Weighing your diamond is a reliable way to test its authenticity. You'll need a gram scale or carat scale to weigh the stone. Cubic zirconia, the most popular fake diamond, weighs about 55 percent more than a diamond of the same size. To test, place your stone on the scale and note its weight. Next, place a cubic zirconia of the same size and shape on the scale and check the weight. If your stone is a diamond, it will weigh less. If it's a fake, it will weigh about the same as the cubic zirconia.

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