How can you spot a fake diamond?

Diamond Certification Questions

How can you spot a fake diamond?

A buyer should be less afraid of “fake diamonds” and more cautious about the seller representing a diamond stone as accurately as possible. When the diamond is accompanied by a third-party certificate, it is more likely to be what the seller claims it to be. All other purchases are less certain.

For some people, a diamond is a diamond. For others, only a natural diamond is a diamond. However, diamonds can be created in laboratories, and other materials can be used to create gems that resemble diamonds closely, such as cubic zirconia, moissanite, crystal, and rhinestones. And for some people, even a natural diamond is a “fake” if it has been enhanced. With so many definitions of fake, it is best to break this question down to address each style of “fake” diamond.

How can I spot a laboratory manufactured diamond?

  • Ask the seller/owner where the diamond originated. An honest person will tell you what he knows.
  • Look for the phrases “man-made diamonds,” “cultured diamonds,” or “laboratory grown.” The phrase is not required to be shown on the certification, but it is often used in displays to help customers know the difference between natural and cultured diamonds, similar to how pearls are classified.
  • The laboratories that manufacture diamonds ask that jewelers display their brand names. Look for names such as Gemesis, Apollo, Sona, Takara, and Chatham.
  • Ask to see what is inscribed on the diamond. The laboratory manufacturing the diamond usually laser inscribes the company name, plus an identification number, after the diamond has been polished.
  • If you are still in doubt, ask a gemologist to inspect the diamond. A laboratory grown diamond may contain a small amount of nickel or other metal used as the catalyst. After intense ultraviolet light exposure, the trace catalyst can cause is a short-lived phosphorescence; most natural diamonds will not show the phosphorescence. Also, the gemologist can use an X-ray absorption spectroscope or a transform-infrared spectroscope to distinguish differences in the distribution of nitrogen defects.

How can I spot a “diamond” made from other materials?

  • Look for the phrase “synthetic diamond.” While sometimes this phrase is mistakenly used for man-made diamonds, it usually indicates an inferior material is being substituted.
  • Look for scratches. While real diamonds acquire scratches, chips, dents, and the like over time, other materials show the wear and tear much faster. If you see visible scars, be on alert. And if you, a non-gemologist, can see visible scars on a natural diamond, expect the diamond to be priced much lower than Rapaport value.
  • Place the loose diamond over newsprint and attempt to read through the diamond. If you can read through the diamond, it is either a fake or a poor cut (“low cut”).
  • Breathe on the diamond just as you would to fog a window. If the fog remains more than two seconds, it’s likely a fake. Repeat the fog test on the bottom of the diamond; some fakes are crafted with a diamond surface and synthetic underside.
  • Place the stone under ultraviolet light, and watch for blue fluorescence. Medium to strong blue indicates a real diamond. If there is no blue fluorescence, either the diamond is of excellent quality or it is a fake.
  • Look inside the setting for any stamps. “CZ” indicates the stone is cubic zirconia. A stamp such as “10 K,” “14K,” “18K,” “585,” “750,” “900,” “950,” “PT,” and “Plat” describe a setting’s gold or platinum status. High-quality diamonds will be set in high-quality settings, not something gold plated or made of an inferior metal. Of course, a dishonest jeweler could set a fake stone in a high-quality setting—or could even stamp the setting to make it appear of higher quality than it really is.
  • Look with magnification at the stone. Facets should be joined with sharp lines, not rolls. The girdle should have facets; it should not be waxy or slick. Most diamonds have natural internal flaws; most fakes do not.
  • Moissanite, a popular diamond substitute, sparkles greatly in outdoor light but appears dull with incandescent lighting.
  • To keep costs low, fake gems are often machine cut, rather than hand crafted. Machine cut moissanite will not display the “hearts and arrows” seen in hand-cut, natural diamonds.
  • A jeweler may offer to prove a diamond is real by using his diamond tester. Be cautious, as moissanite will frequently fool a diamond tester—and a smart jeweler knows this.
  • When a cubic zirconia stone is submerged in water, the gemstone virtually disappears; a natural diamond is easily visible. The water enhances the two stones’ differences in light refraction.
  • Weigh the stone on a scale you trust. Cubic zirconia weighs approximately 55% more than diamond.

How can I spot a diamond that has had enhancements?

  • If a high-quality diamond is sold without certification, the chances are high that it has either been enhanced by “cosmetic surgery” or is a blood diamond. An independent inspection by a graduate gemologist (GG) will reveal the diamond’s true status and what could happen to the diamond based on its particular enhancement procedures.
  • To improve clarity by one or two grades, some diamonds’ fractures are filled with molten glass or cheaper materials in a process called Yehuda. Fillings are not visible to the naked eye, so you will need to have the diamond independently inspected by a gemologist.
  • Inclusions, such as imbedded crystals or minerals, can be eliminated from a diamond with laser treatment, but the treatment involves drilling tiny holes into the diamond. The holes appear as tiny threads from the diamond surface to the eliminated original inclusion. From one angle, it may appear as just a little dot, but from another angle—usually the side—magnification will reveal the drilled line. Some techniques eliminate a distracting inclusion and leave less distracting inclusions that appear natural, so the assistance of a trained gemologist is needed to tell if a diamond has undergone this cosmetic procedure.
  • Low color grades are sometimes enhanced to a few shades whiter with a high-pressure and high-temperature (HPHT) process. The process leaves diamonds more fragile and brittle and, therefore, more prone to damage. The Federal Trade Commission requires HPHT treated diamonds to be labeled as such. Look at the diamond’s certificate, in the color section, for the phrase “HPHT processed, irradiated” or “HPHT annealed” or “artificially irradiated.” Spotting a HPHT diamond requires the assistance of a gemologist, who can use an SSEF spotter, crossed polarization filter, or spectroscope. If your diamond is smaller than half a carat, it is not likely to have been HPHT processed.

If you absolutely want a natural diamond, tell the seller that’s the only thing you want, and inspect the diamond’s certificate. And if you would rather get a low-price diamond substitute, keep these tips in mind so you know how to treat your fake so it won’t be spotted by others.