Whenever you have a highly valuable, coveted gemstone like diamond, you’re going to have fakes. Of course, nobody wants to be fooled into paying top dollar for a cubic zirconium, moissanite, or even glass fake that is being passed off as a real diamond. People are justifiably wary of falling for an imitation, because some counterfeit diamonds look convincingly real. So how can you avoid getting scammed?

Of course, the only way to be 100 percent sure that the stone you have is a real diamond is to have it professionally appraised. Some DIY methods of trying to determine whether or not a diamond is real aren’t easy to carry out if you do not have special equipment or if the stone is already in a setting, and they may damage the stone you’re trying to test. But there are some safe, quick ways you can separate out inauthentic stones before you go to the trouble of seeking out the opinion of a gemologist.

1. The fog test: Genuine diamonds do not retain heat well. If you breathe on them as if you were trying to fog up a mirror or a pane of glass, any haze you manage to produce on the stone will dissipate quickly. A fake diamond such as moissanite, on the other hand, will build up condensation as you breathe on it. (Make sure the gem is clean before you try this; dirt and oil buildup on the stone can affect your results.)

2. Examine the setting: It is highly unlikely that a genuine diamond would be mounted in a cheap base metal setting. Check for symbols that indicate the setting is a precious metal, such as 10K or 14K for gold, 925 for sterling silver, or Plat or Pt for platinum. While a precious metal setting is no guarantee that the stone you’re looking at is a diamond, it is much more likely to be a precious or semi-precious gemstone. If the setting has rough edges, an obviously fake finish, wear that exposes dull metal underneath a coating, or is magnetic, then you’ll know it isn’t precious metal.

3. Look at the edges of the stone: A diamond’s edges will be sharp and exact. An imitation diamond, especially one made of glass or a polymer, is more likely to have dull or worn-down edges. While a sharp edge won’t guarantee you have a real diamond on your hands, a dull edge is likely to indicate that you don’t.

If you’re considering investing in a diamond, taking the trouble to obtain an official appraisal is worth the cost. Of course, reputable sellers regularly provide appraisal reports from gemological laboratories for the diamonds and other fine jewelry available on their site, as we do on ours.