Fueled by the perception of rarity, exclusivity and longevity, diamonds pull in about $50 billion a year. It is not surprising that a whole second industry--the diamond simulant industry--sprang up to feed off of that image. While they will never carry the same allure held by real diamonds, diamond simulants like cubic zirconia (CZ) and moissanite serve a purpose by making the diamond mystique accessible to those who could not otherwise afford it. The quality and appearance of diamond simulants has improved dramatically over the years, but there are still several key differences to be found when comparing simulated diamonds to real ones.
Examine them through a 10x jeweler’s loupe. Simulated diamonds typically have no inclusions or flaws-something that is extremely rare to find in nature. Natural diamonds often have small imperfections in it, like lines, cloudy spots, black specks and “bubbles” in patterns that are unique to each diamond. Inclusions are how jewelers identify one diamond from another.
Look at the stone’s color. CZs are naturally colorless. Moissanites are rarely white and have a slight greenish tinge to them. This test is best done with loose, unset stones in a small white paper tray that lets you see through the side of the stone.
Look at the reflection of light in the stone and its dispersion. This is the “rainbow” effect when light is broken down by the prismatic effect of the cuts in a diamond. Moissanite double refracts, which means that there is more of a rainbow effect in it than in a real diamond. CZs can often look flat and not as brilliant as a real diamond, due to the fact that because CZs are so cheap, not that many are hand cut to the quality of real diamonds. A trained eye can see these qualities; the average person may not.
Do a scratch test. Diamonds are the hardest substance on earth--a perfect 10 on the Mohs hardness scale. The only thing that can scratch a diamond is another diamond. No diamond simulant is that hard, so you can scratch a diamond simulant with a diamond, but not the other way around.
Observe a stone worn in a ring or a bracelet for any wear on the facets or table. If there is any, then it is not a diamond and is probably a CZ, since there isn’t anything hard enough out there to wear away the facets on a diamond except another diamond.
Take the stone to a trained, knowledgeable and trustworthy jeweler. A jeweler with a lot of experience with loose diamonds, or one with a Graduate Gemologist (GG) certification, should be able to perform a few tests to be sure. Very few jewelers can tell whether a stone is a real diamond or not, especially if it is a very well cut, good quality one, just by glancing at it.