When you place a real diamond underneath an ultraviolet light, the stone with fluorescence in it will turn blue. But it's important to know that this will only happen with about one-third of all diamonds. A fake diamond, on the other hand, will almost never look blue under a black or UV 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.
Usually fluorescence is blue in color. Less often, a diamond can have yellow or even white fluorescence (other colors too). Diamonds with Strong - or Very Strong - fluorescence can appear quite cloudy, milky or hazy to the naked eye, and emit a prominent and saturated glow in the presence of UV light.
Some diamonds fluoresce when they are exposed to long-wave ultraviolet (UV) rays from sources like the sun. This can cause them to emit a bluish light or more rarely, a yellow or orangy light. Once the UV light source is removed, the diamond stops fluorescing.
A real diamond appears gray and white inside (brilliance) when held to the light and can reflect rainbow colors (fire) onto other surfaces.
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.
Fluorescence is the visible light that a diamond emits when it is exposed to the UV rays. Fluorescence is naturally occurring, and at it's best it can make off white diamonds look whiter or more colourless. Around 30% of diamonds evaluated by the GIA have varying degrees of fluorescence detailed on the certificate.
Diamonds glow in black lighting due to a phenomenon called fluorescence and roughly 35% of natural diamonds exhibit some degree of this effect. In nature, the presence of certain chemical impurities within the diamond's composition triggers this glowing effect in the presence of an ultraviolet light source.
You will see a glow in 30% of diamonds under a UV light. When exposed to UV light, there will be a diamond glowing in different colors. 99% of the time, the glow is blue, but on rare occasions, diamonds glow white, yellow, green, or even red in color.
Diamond fluorescence refers to the intensity of a coloured glow (usually blue) that is visible when a diamond is exposed to UV light. In some instances, diamonds with strong fluorescence may look milky and lifeless in daylight, but in most cases, the appearance of a diamond with strong fluorescence is rarely affected.
The phenomenon that causes a diamond to glow under black light is called fluorescence. Around 35% of diamonds grown naturally have this component in them, and 95% of them glow a bluish color when exposed to a black light.
This involves taking the diamond and attempting to scratch a mirror. If it leaves a mark on the mirror, it's a real diamond. However, the quality of false stones like cubic zirconia and moissanite has increased, and many can pass this test due to their durability.
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.
So, is diamond fluorescence good or bad? Well, that depends. The more expensive diamonds (large and high color, think D-E-F) are far more valuable when they exhibit no fluorescence. But for most other diamonds, especially diamonds with Faint fluorescence, this phenomenon rarely impacts the diamond's visual nature.
A diamond that has not been cleaned for a while can look milky due to a buildup of film and dirt on its facets. Cloudy diamonds can also have diminished transparency from inclusions or other characteristics intrinsic to the crystal from which they are cut.
A completely colorless diamond looks bright white. All diamonds, however, come in three tints — yellow, brown and grey that can range from nearly imperceptible to quite obvious.
Fluorescent test using a regular UV light source will help to distinguish Natural Diamond vs CZ. Cubic Zirconia will not fluoresce unlike Natural Diamonds Fluoresce of about 25% to 30%.
Purchase a cheap piece of corundum or buy a mineral testing kit that includes corundum. Hold the corundum firmly against a table and scrape the suspected diamond against the corundum. If it creates a visible scratch, the crystal is a diamond. If it doesn't create a scratch, then it is a different mineral.
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.
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.
There is nothing that can scratch a diamond except another diamond. A mineral like talc, on the other hand, is a 1 on the scale. You could scratch it with any hard material, even your fingernail. Natural talc is one of the softest minerals in the world.
Take your diamond between two fingers and blow a puff of air into it. The moisture and heat from that air will fog up your stone. If this fog dissipates quickly, your diamond is real and if it takes a while to dissipate then you need to re-evaluate your jeweler. Diamonds conduct heat and disperse it quickly.
A real diamond of decent quality will refract light so intensely that you can't see through it. On the other hand, cubic zirconia is more transparent, and you'll be able to see right through it.