Gemstone Fluorescence: What is it?
When light or any other form of energy energizes a gemstone, it emits color. The phenomenon is known as gemstone fluorescence. It is a type of luminescence.
Gemstone Fluorescence
In most circumstances, the released light has a longer wavelength than the absorbed radiation and has lower photon energy.
Is Gemstone Fluorescence Good Or Bad?
Some diamonds will also display this spectacle, and the price of such diamonds usually declines. However, when rubies do this, their cost rises.
Why is that? Because the fluorescence reaction in various stones varies, sometimes it enhances the beauty of the gemstone, and other times it detracts from it.
In the case of diamonds, a stone with fluorescence might appear foggy or cloudy when exposed to the sun. In rubies, on the other hand, this enhances the red color.
So Let Us Have A Basic Rundown Of What Gemstone Fluorescence Is:
We know that the sun’s light has a spectrum that isn’t merely in the visible region. It also emits ultraviolet and infrared light that we cannot see.
When this composite light hits a gem, the unseen energy streams energize and excite the electrons within the stone. Consequently, the stimulated electrons jump to a higher energy level for a brief moment. Subsequently, they return to their ground state, and while doing so, they start releasing their absorbed surplus energy. We see this discharged energy as the fluorescent glow.
When viewing a strongly fluorescent ruby or red spinel in the sunshine, they appear redder. This is because the catchment of UV rays from the sun makes them fluoresce. As a consequence, the gems look way better in daylight. Stronger light entering the stone, coupled with the color emitted by the jewel, enhances the appearance of the stone. In the case of rubies, the phenomenon is poetically called the “blushing of rubies.”
If you’re indoors, though, you won’t notice nearly as much red. Thus, we comprehend that fluorescence adds to the vibrancy of these stones.
An Experiment:
Scientists devised an experiment to check this phenomenon and the source of the enhanced red color. First, they exposed a ruby gem to light. But, they filtered out the red band entirely from the light entering the stone. They thus ensured that if any red came out of the stone, it would not be from the light source.
Next, on the other side, another filter took out bands of all colors except red from the exiting rays. Under such a scenario, since no red was going into the gemstone, no red should come out. And yet, they could see red on the lens on the other side. Therefore, they concluded that the red is coming out of the stone itself because of fluorescence.
Mineral Agents That Cause Fluorescence:
But what is the source of this phenomenon? A variety of factors can cause fluorescence. Nonetheless, it is most typically caused by colorful gemstones using two catalysts.
Firstly, it is Chromium, which we view as either red or green. So the red we see in rubies and spinels is due to Chromium. Further, Chromium is also responsible for the green in emeralds. Additionally, Vanadium and a small amount of iron may also tint emeralds. And yet, Chromium is the one responsible for the fluorescence in these stones, whether it’s red in rubies and spinel or green in emeralds.
Secondly, gemstone fluorescence can be triggered by Cobalt as well, and we see this mainly as the vivid blue color in gemstones. Furthermore, it is also the brilliant blue glaze that you’ll find on many earthenwares. Thus we see that both Chromium and Cobalt can induce this spectacle.
Impact on Gemstones:
The phenomenon alters the gem colors slightly from the original, and the difference is not overly noticeable. The body color changes moderately, and there is no dramatic change.
In stones with high fluorescence, the color takes on a life of its own. It acquires a bold, three-dimensional character, and a hauntingly beautiful appearance lends itself to the stone.
Role Played By Iron:
Iron inhibits fluorescence. So, for example, some stones might have a lot of Chromium, but a simultaneous presence of a lot of iron smothers the fluorescence.
Remember that gemstone fluorescence is caused by molecules of certain compounds in a stone when light strikes them. The incident light beams excite them, and they start releasing color. But iron, if present, plays the complete spoil-sport. It puts an abrupt end to any such activity.
Aide To Gemologists and Gem Buyers:
Geologists use this knowledge to identify different types of gems and their geographic origins. Rubies from Thailand, for example, are high in iron, but rubies from Myanmar or Burma and Afghanistan are low in iron. So Myanmar (Burma) or Afghanistan rubies will glow if you put a black light on them. But, on the other hand, when the same black light shines on a Thai ruby, it doesn’t look exciting in comparison. And that’s because the iron in the Thai ruby will douse that fluorescence.
The same is true for emeralds from different geographical regions. For instance, Emeralds from Colombia and Afghanistan typically have low iron content, and the available iron quantity is not enough to snuff out that fluorescence reaction here. For viewing the glow, though, the same black light that helps rubies to fluoresce is limited in its ability to help emeralds.
Therefore, you will have to flash a torch on it instead and use a dichromatic Chelsea filter (it filters out specific wavelengths of light). If this gem has a high chromium content, you will see a red or pinkish glow to it. On the other hand, low Chromium or high iron content will not elicit any reaction from the stone.
As such, the exceptional levels of pink or red reveal a lot about the stone. At the same time, they also offer you a solid indication of where the stone originated from or what sort of stone it is. This data has many applications in a variety of different gemstones. First, however, you must be knowledgeable about the stones you’re considering.
Does Aquamarine Fluoresce?
Another example of gemstone fluorescence is Aquamarine. This gem is colored mainly by iron. We rightly expect the surfeit of iron to dampen its fluorescence. Consequently, a Chelsea filter should not be able to show us any fluorescence whatsoever in Aquamarines. And so, in case someone tries to pass off synthetic cobalt spinel as Aquamarine to you, this knowledge can come to your help. You can use the Chelsea filter and a light source to test the fakes. The test will show you the tell-tale glow of fluorescence and call out the fakes.
Again, different varieties of red stones are colored differently. Some red jewels are tinted by Chromium, while other chromophores color others.
Deeper rubies and brilliant red garnets can confuse you to misidentify one for the other. Nonetheless, you can use a black light and a Chelsea filter to sort out garnets and rubies and overcome this problem quickly.
Now, understand me; the above examination is not a magic bullet. You certainly need to conduct more tests. But, it will give you a good idea of what you should learn more about the gems.
If you’re trying to identify rubies, this is an excellent place to start. It won’t tell you the difference between rubies and spinel, though. You have got other tests for doing that.
For now, we are talking about blushing gemstones.
Summary:
Gemstone fluorescence occurs when energy hits atoms inside a gemstone. The incident energy excites the particles, and they start emitting color. This color can be different from the body color of the jewel. Chromium and Cobalt are the typical fluorescence-inducing catalysts.
You can test certain varieties of fluorescence using a Chelsea filter or a black light gemologist torch. At times, you might need a shortwave fluorescence torch to do that. But, experts with requisite and adequate precautions should only use such a shortwave torch because it is carcinogenic (cancer-causing).
Iron has the property to extinguish the fluorescence effect. So, if you have a stone with a lot of Chromium and also a lot of iron, for example, it might not fluoresce. Of course, this doesn’t prove anything about the stone, but it gives us vital pointers in the right direction. To figure out what those pointers are, you’ll need a detailed understanding of your stones.
See Also
| Phenomenal Gemstones | Asterism in Star Gemstones |
| Chatoyancy | Adularescence and Labradorescence |
