Diamonds are dense and will sink quickly, while certain imitations will sink more slowly. If your gem doesn't immediately sink to the bottom, it's likely a glass or quartz imitation. However, other imitations, including cubic zirconia, will also sink quickly.
The floating test:
If the diamond is real, it will drop to the bottom of the glass due to the high density of the stone. If the diamond is a fake, it will float on the surface of the water. Not all fake diamonds float in water so don't take the results of this test as conclusive.
Water Test
If you have a loose diamond to test, fill a regular glass about ¾ of the way full with water. Gently drop the diamond into the glass. If the diamond sinks to the bottom, it's real. If it floats at the surface or just underneath, it's likely a fake.
True diamonds have high density and should quickly sink to the bottom of the glass. Fake diamonds are not as thick, and therefore, more likely to float in water.
Fake diamonds do not reflect spectral rays from the beam of the flashlight. This is because a diamond's refractive index is high; it makes the white light entering the diamond split into multiple colors before it exits on the other side of the stone.
As straightforward as it sounds, fill a glass of water at home to roughly three-quarters full. Separate the stone so that it is loose, and drop it into the water. Diamonds are highly dense and a genuine gem will sink to the bottom – every time. If it hovers to the surface or only partially sinks, then it is a replica.
The differences between Natural Diamonds and Lab Grown Diamonds cannot be seen with the naked eye. Natural Diamonds have tiny amounts of nitrogen, while Lab Grown Diamonds have no nitrogen. This is actually one of the signifiers gemologists use to identify if a diamond is lab grown or natural.
A real diamond appears gray and white inside (brilliance) when held to the light and can reflect rainbow colors (fire) onto other surfaces. A fake diamond will display rainbow colors within the stone when held up to light.
A fake diamond will have rainbow colors that you can see inside the diamond. “People have a misconception that diamonds sparkle like a rainbow, but they don't,” Hirsch said. “They do sparkle, but it's more of a gray color.
Place the gemstones in a glass of water and watch. If it floats, then it is probably a fake stone. Real diamonds will sink to the bottom of the glass, while cubic zirconia will float to the surface.
A diamond placed in water, the critical angle gets the increase that causes the lower number of reflection. Thus the diamond under water is sparkle less than in air.
The free 4Cs app for Android is downloadable in English and Simplified Chinese. The GIA app is also available for iOS. A retailer version, designed for use at point of sale, is downloadable for free from GIA's retailer support site www.retailer.gia.edu.
Plastic and glass jewelry are generally okay to wear in the shower and at the beach. Simply wipe them down when you dry off or take them out to air dry. Be careful of any baubles or filigree that may come loose or be damaged on glass and plastic pieces.
Simulated diamonds are also known as diamond simulants and include things like cubic zirconia (CZ), moissanite, and YAG. They can also include some natural clear gemstones like white sapphire, white zircon or even clear quartz.
Most synthetic diamonds look too good to be true all due to their extreme brilliance. Does your stone look really bright with lots of rainbow reflected colors? If so, it's most likely cubic zirconia. Yes, real diamonds are brilliant, but they are much more subtle than synthetics.
If you're holding a genuine diamond, you'll witness an intense blue color on the diamond surface. A fake gemstone will reveal itself through other colors — including green, yellow, or gray tints. The validity of this test is limited, though.
A pure and natural diamond is known to produce a blue glow when exposed to black light. The impure ones have certain chemical impurities that trigger the glow of other colors like green, white, red, and yellow when diamonds are exposed to ultraviolet light.
Ultraviolet Light: About 30% of diamonds will glow blue under ultraviolet lights such as black light. Fake diamonds, on the other hand, will glow other colors or not at all.
Professional jewelers and gemologists cannot tell the difference between a lab created diamond and a natural one just by looking at it with the naked eye. They will have to use a microscope to look for the tiny differences in its inclusions that indicate how it was formed.
By holding a diamond close to a source of light, such as a flashlight, you can tell whether or not it's real. Watch closely for the shimmers of light that shine from the stone. A real diamond will reflect light easily, and provide you with a disco ball or rainbow-like display.
Genuine diamonds do not sparkle in rainbow colors inside of the stone. Instead, the inside of real diamonds sparkles in tones white and gray. The play on light in the diamond is brilliance. One factor that determines a diamond's level of brilliance is the cut.
If the small stones on your diamond engagement ring are between 1 and 2 points (0.01-0.02 carats), it may be appraised at a price range of $300 to $700 per carat. Larger chips or stones at 0.10 carats may result in you being able to get $1000 or more for your jewelry if the diamonds score high on clarity and color.
Can fake diamonds pass diamond tester? Yes, some diamond simulants can pass a diamond tester. For example, moissanite, a man made gem, may pass as a diamond on a standard tester pen. This is because moissanite also has very high thermal conductivity!