Left to right: visible light, shortwave UV, and longwave UV.
"Which UV light should I buy?" When I was looking for my first UV light, there didn't seem to be a lot of easily accessible information on the topic, and what little I did find seemed to only confuse me more. Hopefully this short page will serve to point beginners in a helpful direction.
When choosing a UV light, determine your needs/wants:
Not all UV lights are the same, and that doesn’t just mean in quality. The wavelength is one of the most important factors and will greatly influence how many and which minerals will actually “glow”. Be aware: many UV light sellers, especially cheaper brands, will not mention the wavelength. Avoid these.
When choosing a UV light, determine your needs/wants:
- Do you need a shortwave, midwave, or longwave UV light? If you're not sure how to answer this, no fear! Read on!
- Will the lamp be used primarily inside, or will you need to take it outside? (In other words, will you be looking at your mineral collection at home, or rockhounding in the field?)
- What is your budget?
- Is your goal to “test the waters” of the fluorescent mineral hobby just for fun, or are you looking for a light that won’t need upgrading for a while?
Not all UV lights are the same, and that doesn’t just mean in quality. The wavelength is one of the most important factors and will greatly influence how many and which minerals will actually “glow”. Be aware: many UV light sellers, especially cheaper brands, will not mention the wavelength. Avoid these.
It’s important to know which wavelength of UV light you want. But how do you decide? What’s the difference? The video below shows how four different rocks respond to three different types of UV (longwave, midwave, and shortwave). Some of the pieces only fluoresce under certain wavelengths while others fluoresce different colors under each wavelength, or with varying brightness.
There are three common ultraviolet wavelengths used in the fluorescent mineral hobby.
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Longwave UV
Longwave UV is the most popular choice. It has a wavelength range of 315-400 nanometers on the electromagnetic spectrum and is also known as UVA. Most blacklights fall into this category but avoid these as they are often closer to 400nm and rarely, if ever, have a filter to block visible light. This is a great wavelength to choose if you’re on a budget, need something that has a longer battery-life, and just want to casually see what the fluorescent world has to offer. |
Scapolite under filter, longwave UV (365nm).
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Pros: Easy to find lights in this wavelength, many of which are budget friendly. It is also easy to find flashlight versions that can be carried around outside.
Cons: Fewer minerals are responsive to this wavelength. Sodalite (including “yooperlite”, a trade name for syenite with a high amount of sodalite) and calcite are typically the most common to glow.
Recommendations: Pick a light that is very close to 365nm; this has been found to be one of the best wavelengths for longwave response in minerals. If choosing a budget light, be sure that it has a filter! (See sections below to learn why this is important.) My recommendations for longwave lights are the UV Beast Mini and the Convoy C8; both are flashlights. Or choose the LNKR Longwave LED lamp for an inexpensive way to flood light over a display shelf.
If you are in Europe, Colorgems.nl makes similar lights of excellent quality.
Cons: Fewer minerals are responsive to this wavelength. Sodalite (including “yooperlite”, a trade name for syenite with a high amount of sodalite) and calcite are typically the most common to glow.
Recommendations: Pick a light that is very close to 365nm; this has been found to be one of the best wavelengths for longwave response in minerals. If choosing a budget light, be sure that it has a filter! (See sections below to learn why this is important.) My recommendations for longwave lights are the UV Beast Mini and the Convoy C8; both are flashlights. Or choose the LNKR Longwave LED lamp for an inexpensive way to flood light over a display shelf.
If you are in Europe, Colorgems.nl makes similar lights of excellent quality.
Midwave UV
Coming soon. In the meantime, here are the midwave lights I recommend: the B310-4 High Power and the B310-1 Mini flashlights.
Coming soon. In the meantime, here are the midwave lights I recommend: the B310-4 High Power and the B310-1 Mini flashlights.
Autunite (radioactive) under filtered shortwave UV (254nm).
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Shortwave UV
Shortwave is the second most common wavelength used in the fluorescent mineral hobby; however, it is the one preferred by serious collectors. The wavelength is about 200-280 nanometers and is the most dangerous of the three UV wavelengths discussed here, so precautions should absolutely be taken. It is also known as UVC. This is a great wavelength to choose if you want to see more minerals fluoresce, although typically the prices start higher. |
Pros: More minerals fluoresce under shortwave UV than any other wavelength. Often a mineral will only respond under shortwave, so it is easily the best choice if your goal is to see a wide variety of mineral fluorescence.
Cons: Price. Because shortwave UV lights require a specialized filter, the cost is noticeably more than that of longwave. In the past, flashlight versions of shortwave lights were not available, but recently this has changed. You may also notice these lights run quite a bit hotter than longwave.
Recommendations: Choose a light as close to 254nm as possible. Unlike longwave lights, shortwave will appear to have less output, so going with the highest possible wattage you can afford is ideal. I recommend the 15-watt GLW Stick or the 35-watt BLCK Widow, although both must be plugged in. Engenious Designs also makes two shortwave flashlights that you can find here.
If you are in Europe, Colorgems.nl makes similar lights of excellent quality.
Cons: Price. Because shortwave UV lights require a specialized filter, the cost is noticeably more than that of longwave. In the past, flashlight versions of shortwave lights were not available, but recently this has changed. You may also notice these lights run quite a bit hotter than longwave.
Recommendations: Choose a light as close to 254nm as possible. Unlike longwave lights, shortwave will appear to have less output, so going with the highest possible wattage you can afford is ideal. I recommend the 15-watt GLW Stick or the 35-watt BLCK Widow, although both must be plugged in. Engenious Designs also makes two shortwave flashlights that you can find here.
If you are in Europe, Colorgems.nl makes similar lights of excellent quality.
Filtering out visible light is incredibly important. Without a filter, the UV wavelength can be overpowered by visible light and all you see is a purple or blue glow. This is why blacklights (longwave) or germicidal (shortwave) lights are nearly useless for looking at fluorescent minerals. Most good brands will already have a filter installed and will mention this in the item description. However, if it's not stated, you can always reach out to the seller for confirmation that a filter is already fitted on the light, or if you will need to install one yourself (I do not personally recommend this as several good brands already do this for you).
For more information, Natures Rainbows has some excellent and easily understandable information. Click here to find out what they say about filters.
For more information, Natures Rainbows has some excellent and easily understandable information. Click here to find out what they say about filters.
Ultraviolet light can be harmful to humans, with the potential to cause sunburns, cancer (with prolonged exposure), and other health issues. It is best to always wear eye protection such as goggles or wrap-around safety glasses regardless of the wavelength. Most shortwave UV is blocked by regular plastic and glass but always check the manufacturer's specifications to determine what wavelengths your glasses or goggle are rated to protect you from. Another good precaution is to wear gloves and long sleeves when handling specimen under UV lights, particularly with shortwave. And it should go without saying, but never point an ultraviolet light source toward your face. For a detailed report on how different types of UV radiation effects the skin, the paper "UV Radiation and the Skin" by D'Orazio et al is a good place to start. Please note that this is not medical advice and is for general informational purposes only.
Links
- Nature's Rainbows naturesrainbows.com - An excellent reference site.
- Fluomin fluomin.org- A fluorescent mineral database.