Lab-grown diamonds are no exception when it comes to exhibiting fluorescent properties – they, too, have been known to luminesce under UV lighting conditions, just like mined diamonds do. However, as we'll explain below, lab-created diamonds display fluorescence much less frequently.
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.
The most likely cause of fluorescence in man-made diamonds is heat treatment and irradiation processes. Though these processes are usually used to enhance desirable yellow or pink colours, they can also cause the stone to react to UV light like natural diamonds.
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.
As a final note on fluorescence, lab-grown diamonds (other than fancy color lab-grown diamonds) never have fluorescence. We think in time this fact could make fluorescence in a natural diamond a more desirable and valuable trait since it serves as a natural differentiator to lab-grown diamonds.
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.
It's also worth mentioning that some lab-grown diamonds may be treated with a process called irradiation. This process involves exposing the diamond to a high dose of radiation, which can cause the diamond to emit a visible light when exposed to ultraviolet light.
They can be colorless, brown, faint pink, blue or black. HPHT (high pressure high temperature): this is the best-known technique. HPHT subjects carbon atoms to very high temperatures and pressures, re-creating the geological conditions in which diamonds crystallize.
Cubic Zirconia (CZ) often shows orange fluorescence but in REVERSE ORDER. This reversal is a sure test for diamond versus CZ. vs.
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.
Test your stone by putting it in direct sunlight and examining the colors it reflects. A real diamond will reflect both rainbow colors as well as white light. If you only get one of the two, then the diamond isn't real.
The way that diamonds reflect light is unique: the inside of a real diamond should sparkle gray and white while the outside should reflect a rainbow of colors onto other surfaces. A fake diamond, on the other hand, will have rainbow colors that you can see inside the diamond as well.
Sometimes, tiny amounts of impurities in diamonds can cause them to glow or luminesce under UV light. UV diamond fluorescence occurs in about 35% of colorless (white) diamonds and can be faint or very strong. (Fluorescence is a type of glow that occurs almost immediately after exposure to UV 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. According to the GIA diamond report, more than 65% of diamonds lack fluorescence.
All CVD synthetic Diamonds, regardless of color, are magnetically inert (diamagnetic) and cannot be separated from natural Diamonds by magnetic response.
Unlike natural diamonds mined from the earth, lab diamonds won't usually gain value. In fact, in recent years, their value hasn't kept up with inflation, mostly due to the increased availability of lab-grown gemstones. So, to put it simply: a lab-grown diamond isn't going to bring much, if any, return on investment.
While lab grown diamonds circumvent environmental issues with mining, they create sustainability problems of their own. The heat and pressure needed to create a lab grown diamond demands huge amounts of energy.
In cut stones, cubic zirconia tends to have dull, rounded edges, while diamonds' facets stay sharp. Diamonds rarely show polish marks, but if they do, they will be in different directions on different facets. On the other hand, cubic zirconia will show polishing marks in the same direction on adjoining facets.
Real diamonds sparkle differently from fakes, but without experience it's difficult to recognize the differences. A well-cut diamond will have a good mix of white light, called brilliance, and flashes of color, called dispersion. Diamonds also display a strong contrast of light and dark areas.
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.
Lab-Grown Diamonds
Other names for lab-grown stones are synthetic, engineered, and cultured diamonds. They exhibit the same chemical and optical properties as mined diamonds. As such, lab-grown diamonds sparkle rainbow colors in the same way as earth-grown stones.
Some people feel that lab-made diamonds are inappropriate for an engagement ring because they're "cheap." Others say that a diamond is a diamond, whether it came from the ground or a laboratory.
Moissanite, being a lab-grown gemstone with a different chemical composition, has a unique luminescent behaviour under blacklight.
Man made diamonds are difficult to spot because of their chemical, physical and optical properties similar to their natural counterparts. Professional jeweler services and pawn shop brokers often have the equipment needed to tell the difference.