You’re fascinated by crystals, or you wouldn’t be here, right? And you’ve heard of ultraviolet light. But did you know that there are tons of crystals that glow under UV light? If you've been following me on Instagram, you know I love finding all of these awesome UV reactive crystals! It is a fun surprise sometimes when I get home from gem shows and I bust out my UV light in the room full of new crystal babies.
If you’re as curious as I was when I first learned about this incredible phenomenon, then read on, we’ve got it all covered for you right here.
What is a UV Reactive Crystal?
In the simplest terms, this is any crystalline structure that glows in the presence of UV light. The mineral content of the crystal will determine if it is fluorescent and to what extent. Every mineral can reflect light but some have the additional property of being able to capture a fraction of this light, hold it momentarily and then emit it at a later time and at a different wavelength.
This property is known as fluorescence and under UV light can give the impression that the stones or fluorescent crystals are the origin of the light source.
Why Do Some Crystals Glow Under UV light?
The presence of some specific light wavelengths from cathode rays, x-rays, and of course UV light excites receptive electrons within the illuminated mineral. The reactive electrons briefly move to a higher orbital position inside the atomic structure of the mineral. This is essentially the moment that the light is 'trapped' as energy within the material. When the electron returns to its lower orbital position, or 'falls' back, that light energy is released in the form of a beautiful fluorescent glow.
Additionally, not only is the light released, but it is very often quite different from the wavelength of the light normally reflected from a full spectrum light source, thus making the crystal glow with a different color than is observed in daylight.
The key factor here is the change in wavelength after the return of the excited electron to its original orbital position. As the wavelength changes, so does the color.
The effect is best observed in a dark room, with only UV light reflecting from the surface. UV light is invisible to the human eye, so only the reflected and altered light will be visible. In other words, we don't see the light as coming from the UV device, but only the reflection from the crystal or stone. This gives the truly wonderful impression of the gemstones glowing magically in the dark.
If that isn’t a magical property of nature and physics, then I don’t know what is!
Do Crystals React Differently to Longwave Vs Shortwave Light?
Yes, they do! And if you are interested in this as a hobby then it is important to know the difference.
UV light lies just outside the edge of the visible spectrum where you find purple. It varies in wavelength from 100 to 400 nm (nanometers). Shortwave is found from 200 to 280nm, midwave from 280 to 315nm, and longwave from 315 to 400nm.
There are some minerals that will glow under both light sources, as well as the less commonly talked about midwave light. There are some stones that will glow in only one wavelength. There are also some amazing crystals that will emit different colors specific to the wavelength of the light that they are fluorescing under.
Longwave UV light or 'black light' is the most well-known and is effective in illuminating about 15% of all fluorescing minerals. Longwave lamps are the cheapest and are a good place to start if you are thinking of buying a lamp.
Midwave UV light is becoming more commonly known as lamps in this range are being made more available. Some minerals fluoresce only in this light or may exhibit a different color to that released under LW and SW light. This can be a really fun way to explore stones in a new way that you may already have seen under either of the other two wavelengths.
Shortwave is certainly the most popular UV source among enthusiasts and will elicit fluorescence from the majority of all stones that glow magically in the dark. However, although more useful, these lamps tend to be more expensive than those designed for the other two ranges.
What Minerals Glow Under Ultraviolet Light?
There are over 500 of these amazing gems for you to discover. Here are ten of the most popular in no particular order:
- Opal - glows green under UV
- Ruby (corundum) - glows red
- Sodalite - glows orange
Fluorite - watch out for blues, green-white, and occasionally red
- Aragonite - blue, green, yellow, or white
Selenite - lime-green, blue
- Apatite - pink, yellow, violet, blue, white
Mangano Calcite - pink/red
- Sapphire (corundum) - red
Chalcedony - green, white, yellow
*Bonus Stone: Calcite in General - although not always reactive, this particular beauty will give you yellow, white, green, blue, pink, red… almost any color you can think. It’s definitely super cool to look at!
While these are some of our favorites, please note that this is very far from a complete list.
Why do Crystals Glow Different Colors Under UV Light?
Every mineral has a distinct atomic composition, and each crystal has varied mineral content depending upon its origin. When you expose a crystal to UV light, its fluorescence will depend upon its mineral content. Likewise, the fluorescence of each mineral will depend upon its atomic composition.
If you remember from our explanation earlier, a mineral will fluoresce because electrons within its atomic structure have been excited via the specific wavelength of UV light to which it has been exposed. The reactive electrons temporarily jump to a higher orbit, expend their excess energy, and then fall back to their original orbit, emitting a new wavelength of light depending upon the distance and duration of this jump and fall back which are specific to each mineral.
This explains why some minerals with reactive properties will emit light under exposure to UV light and why the light emitted will change depending upon the atomic structure of the active property as well, potentially, as the wavelength of the UV light to which they have been exposed.
Pure mystery and natural miracle explained by physics!
What are the Most Common Types of UV Crystal?
In no particular order, here are five of the more well-known crystals that will glow in the dark under UV rays.
1. Clear Diamonds - Diamonds don't have to be your favorite gem to appreciate the gorgeous blue glow that longwave UV can produce in this stone. In addition to blue you will also occasionally find green or yellow reflected from a clear diamond.
2. Rubies - This stone will glow a vivid red under UV and like diamonds, tends to give a better effect under longwave UV.
3. Yellow Topaz - This stone is interesting in that it will glow yellow under longwave UV and white under shortwave.
4. Cubic Zirconia - Short wave UV is a better choice to bring out the yellow-orange apricot glow of zirconia.
5. Kunzite - This is another gem that changes color depending upon the light source; glowing violet or orange under longwave and violet or white under shortwave.
Remember, this is not a comprehensive list and there are many, many more stones to experience this wonderful effect with.
What is the Best UV Light for Minerals?
Are you ready to take the next step and buy your first UV light? Here’s what you need to know.
There are three basic options for you to choose from; shortwave, longwave, or a combination of both. If you want the best value for money then go shortwave first. Approximately 85% of reactive minerals will glow under shortwave and you can buy some very inexpensive 4-watt hobbyist lamps to get you started.
You can buy extremely low-end, very cheap longwave, 'blacklight' lamps as well, but bear in mind that only about 15% of all fluorescing minerals will react to longwave UV.
The best option for most people, if you are spending a little more, is a combination lamp that can switch between both or operate with both at the same time.
You can find a couple options linked on our favorite products page.
Are UV Crystals Safe?
UV light is capable of giving you sunburn and you should avoid directing it directly into your eyes or onto your skin. While most lamps are extremely low risk, you should still make sure to read any safety warning that comes with the product you bought.
If your hobby turns into something more serious and you invest in a scientific-grade lamps or if you are spending significantly more time working in UV light, then you will need to take some simple precautions. These include wearing UV filtering goggles while you work and avoiding prolonged overexposure of your skin to the light source.
But the risks are very low and easily preventable, so don’t let this put you off this amazing hobby by any means.
If you are ready for some fun, we do have quite a few UV crystals on the website!