Fluorescence | Gemmology Lesson With Marie Chalmers

Fluorescence | Gemmology Lesson With Marie Chalmers

By Marie Chalmers FGA DGA

Why do some Gemstones glow?

That property is called fluorescence, and only 15% of Gemstones exhibit that phenomenon. Let’s have a talk about fluorescence.

26Fluorescence is the emission of visible light; once a material has been stimulated by radiation, which in most cases is ultraviolet light, the Gemstone will look as if it’s glowing. Gems can glow in varying colours so you get red, blue, or green depending on the material and the different elements within it.

Some Gemstones fluoresce under short-wave ultraviolet and some over long-wave ultraviolet, the torches that are readily available in the marketplace tend to be long-wave ultraviolet, and they are the safest of the ultraviolet torches to use. Be extra careful if you’re using short-wave ultraviolet light, which can be quite damaging make sure it only comes into contact with your skin for short periods of time. Never look into the light!!

The Science behind fluorescence:

The electrons within the atoms start off at groundstate when the ultraviolet light is turned on, the electrons get very excited, and they begin to move up to the excited state, when the source is turned off, they drop back down to groundstate, and that is what creates the fluorescence, giving off visible light.

It keeps going on a loop as they get excited and returns to ground state, so you get constant fluorescence and when the torch is turned off the odd few Gemstones actually do something called phosphorus.

Fluorescence is really quite important for Gemmologists. It’s a Gemmologist’s job to make sure Gemstones can be identified correctly as either a natural material, a man-made material or any treatments that have happened to that material. For example, Ruby will glow under ultraviolet light and it actually fluoresces varying amounts.

If you look at this Ruby bracelet, you will see that some of these chips fluoresce with strong fluorescence, some are a little bit paler, and some don’t have any fluorescence at all, and that is due to the presence of iron in the structure. Iron suppresses the fluorescence, so some have more iron than others. This is important for Gemmologists when we’re trying to identify whether this is Ruby. If we were looking at a faceted Stone in a ring, for example, and it had a very very strong fluorescence, it would be an indicator that we would need to check that it’s not a man-made Ruby because it will exhibit extremely strong fluorescence.

If you’re looking to purchase Ruby Zoisite, there is a lot of fake material in the marketplace. Fluorescence is a really good indicator; grab your torch, and see if it fluoresces, if it fluoresces under ultraviolet light, then it is likely to be Ruby, but the fake stuff, which is a dyed material, is not going to fluoresce, so this is a great quick tip on how to identify Ruby Zoisite.

Fluorescence can look really cool, like our Fluorescent Sodalite Palmstones, which is a material from Lake Michigan in the USA. They glow with a bright orange Fluorescence and looks as if the rock is filled with lava.

Some Diamonds also fluoresce and this is quite rare in a Diamond and it’s also quite important when you’re purchasing a Diamond to think about the value of fluorescence, whereas fluorescence being a rare phenomenon, you’d think that Diamonds that fluoresce would hold a much higher value, but it’s actually the exact opposite.

A fluorescent Diamond tends to sit at a much lower value, sometimes up to 50% less, just because they exhibit strong fluorescence. So, do keep that in mind and let Marie know if you’re thinking of purchasing a Diamond and you would like some independent advice.

To look for fluorescence, you need to be in the dark, so stick your Gemstone under the table if you have to; get your fluorescence torch; these are available from across different marketplaces you can normally pick them up for just a couple of pounds, pop the light on if it glows you’ve got fluorescence.


Chalmers Gems was created by two best friends, Marie Chalmers and Sheena Gill, and is founded on the unwavering mission to source the best ethical Gemstones and Minerals in the world and supply them at the best possible price to our customers.

Having spent over two decades in the jewellery industry, Marie Chalmers FGA DGA, heads up our Buying Team. As a qualified Gemmologist and Fine Goldsmith, Marie has worked across continents such as India, Africa and China. Marie has travelled the world building strong relationships and a fantastic supply chain, enabling her to bring you the highest quality products at the best possible price. As well as having spent her career controlling multi-million £’s worth of stock, she is well versed in the global gemstone and mineral supply chain and can access some very unique and rare products.

As one of the UK’s most influential people in the jewellery industry (Professional Jeweller), Marie is committed to building the most exciting and honourable business. This encompasses product development and education, building on the training courses she managed at the Assay Office Birmingham – the world’s largest Assay Office.

Come with us to discover the world’s best Gemstones. At Chalmers Gems, we offer a unique and exciting way to buy and sell Gems from around the world. We travel straight to the source, visiting mines, cutting factories and manufacturers handpicking exotic, high-quality Gemstones and showcase them during our Live Shows, on our website and in our pop-up shop. All the Gemstones we find are exclusive to our international trips and are available for a limited time.

We regularly tour India, learning about the Gemstones with our Marie. This is your unique opportunity to be part of and understand your Gemstone’s ethical journey from the mine to your door.

We host amazing, inclusive Live Events across our social media channels on a regular basis throughout the week, so ensure to set notifications on Facebook & Instagram so as not to miss these.


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