It can help to use a stone you know is real next to the suspect stone and fog both. You can watch how the real one stays clear while the fake one fogs over; if you breathe on fake diamonds repeatedly, you will see condensation start to build up. With each puff, the fake stone will fog up more and more, while the real one will still be clean and clear.
Cubic zirconium (which should pass all of the other tests) usually doesn’t have imperfections. That’s because they are grown in sterile environments instead of produced by chance in the Earth’s laboratory. A gem that is too perfect is more often than not a fake. It is possible, however, that a real diamond will be flawless. Don’t use imperfections as the determining factor in whether your diamond is real or not. Rule out fakes using other tests first. Note that lab-grown diamonds will also normally have no imperfections because they are also produced in carefully controlled environments. Gem-quality diamonds grown in a lab can be chemically, physically and optically identical (and sometimes superior) to naturally occurring ones. This ability to surpass the quality of “natural” diamonds has caused considerable concern among those in the mined diamond business who have lobbied heavily to have lab-grown diamonds distinguished from “natural diamonds”. Lab-grown diamonds are “real” but they are not “natural”.
The newspaper method: Turn the stone upside down and place it on a piece of newspaper. If you can read print through the stone, or even see distorted black smudges, then it probably isn’t a diamond. A diamond would bend the light so sharply that you wouldn’t be able to see the print. (There are a few exceptions: if its cut is disproportionate, the print can still be visible through a real diamond. ) The dot test: Draw a small dot with a pen on a piece of white paper and place the stone over the center of the dot. Look directly down on it. If your stone is not a diamond, you will see a circular reflection in the stone. You won’t be able to see the dot through a real diamond.
Instead, check for “sparkles. " A real diamond will sparkle significantly more than an equivalently-size piece of glass or quartz. You may want to take along a piece of glass or quartz as reference. Don’t confuse sparkle with reflection. Sparkle has to do with the brilliance or intensity of the light that’s refracted by the cut of the gem. Reflection has to do with the color of the light that’s refracted. So look for intense light, not colored light. There is a stone that has even more luster than a diamond: moissanite. This gemstone is so similar to diamond that even jewelers have a hard time telling them apart. To tell the difference without special equipment, hold the stone close to your eye. Shine a penlight through the stone. If you see rainbow colors, that’s a sign of double refraction. This is a property of moissanite, but not of diamond.
Heat testing works for the same reasons that the DIY “shatter” test works. Instead of measuring whether the gem breaks under the pressure of rapid contraction, however, heat probes measure how long the diamond retains temperature. If you want to have your diamond professionally tested, look online to find a reputable jeweler in your area. [3] X Expert Source Cory SchifterJeweler & Certified Jewelry Appraiser Expert Interview. 21 April 2020.
A traditional heat probe test will not be able to tell the difference between moissanite and a real diamond. Ensure that the test is being conducted with an electrical conductivity tester and not a thermal tester. If you are testing a lot of diamonds at home, combination testers can be purchased online or at diamond specialty shops.
To get the best view of the diamond use a 1200x power microscope.
The only way to accurately perform this test is by having a known real diamond of roughly the same size and shape. Without something to compare it against, you will have difficulty determining if the the weight is off.
Though a UV test can help you narrow down your choice of possibilities, if possible, try to avoid relying on the results of this test as definitive indicators of whether or not a diamond is real. As noted above, some diamonds fluoresce under UV light and others do not. It’s also possible for fake diamonds to be “doped” — treated so that they glow under UV light when they otherwise would not. [7] X Research source
If you want to get your diamond x-ray tested, you will either need to submit it to a professional diamond testing lab, or make a deal with your local x-ray imaging center.
Diamond and moissanite have very similar thermal conductivities. If you only use a diamond tester, it will show “diamond” when you actually have moissanite. It is important to test any stone that tests “diamond” on a diamond tester or a moissanite tester. For a professional jeweler, the best option is to just get a combined diamond/moissanite tester.
Cubic zirconia are also known to exhibit a greater spectrum of color than real diamonds when light is focused on the stone. A real diamond’s sparkle and reflection should be largely colorless, while a cubic zirconia can project colored sparkles. [10] X Research source One commonly-circulated test for determining whether a stone is a real diamond is to scratch glass with it. According to popular belief, if the stone scratches glass without becoming scratched itself, it’s a real diamond. However, some high-quality cubic zirconia can also scratch glass, so this test is actually not a definitive way to determine whether a diamond is real or not. [11] X Research source
An appraisal involves two basic steps: first identifying and evaluating the stone in question, and then assigning value. When looking at independent appraisers, it would be ideal to select an appraiser with a Graduate Gemologist (GG) degree issued by a Gemological Institute in your country, who isn’t involved directly in the sale of diamonds. [12] X Research source This way, you can be sure that the science is sound. When you take your diamond to someone for appraisal, be sure it’s someone who’s trusted in your community. However, it’s also a good idea to choose a jeweler who will appraise the stone in front of you, rather than taking it out of your site. [13] X Expert Source Cory SchifterJeweler & Certified Jewelry Appraiser Expert Interview. 21 April 2020.
whether or not the stone is man-made or natural (Note: man-made diamonds are diamonds, just not “natural”. See the section on detecting man-made diamonds for more detail. ) whether or not the stone has been color-altered whether the stone has had permanent or temporary treatment added whether a stone matches the grading documentation provided by a retailer
The best way to check the authenticity of your diamond is to have it certified by an organization like the Gemological Institute of America, or GIA. If there’s a location near you, you can take your diamond to them directly, or you can have it removed from the setting by a professional jeweler, then ship it to the GIA. [14] X Expert Source Cory SchifterJeweler & Certified Jewelry Appraiser Expert Interview. 21 April 2020.
Certificates come with lots of information about your diamond, such as carat weight, measurements, proportions, clarity grade, color grade, and cut grade. Certificates may also come with information that you might not expect a jeweler to give you. They include: Fluorescence, or the tendency of the diamond to give off faint glow when exposed to ultraviolet light. [15] X Research source Polish, or the smoothness of the surface. Symmetry, or the degree to which the opposing facets mirror each other flawlessly.
Just like humans, every diamond is unique. New technology is allowing gemologists to quantify that uniqueness by producing a “fingerprint” of your gem. Registration usually costs less than $100, and can assist in insurance purposes. If a stolen diamond of yours with a fingerprint shows up in an international database, you should be able to retrieve it by showing documentation that proves it is yours. [16] X Research source
