Gemstone Phenomena: Fluorescence and Phosphorescence

| 3 min read

Throughout history, gemstones have been admired for their wonderful colors and optical properties, which have been a source of mystery and intrigue for millennia. Over 3000 years ago, early miners on Topazios Island believed the gemstone Peridot was invisible in daylight and glowed in the dark, therefore they only worked at night.

While today Peridot is still affectionately referred to as the 'evening Emerald' due to its curious luminosity, we now know there is more to it than a magical myth. These visual phenomena bring together science and nature and go by the names of fluorescence and phosphorescence.


Fluorescence produces vivid colors when an ultraviolet light source is directed at a gemstone. Each gem behaves differently when exposed to ultraviolet light – those that are affected by the light in return fluoresce and give off a strong glow while the light source is present. This happens because the ultraviolet light has more energy than visible light, boosting the energy of certain electrons within the gem, causing them to glow with an amazing array of vibrant colors.

Fluorescence can be a useful tool as a means of identification to distinguish a gemstone’s authenticity or value by the color it fluoresces. For example, the famous Blue Diamond known as the Hope Diamond fluoresces a fiery red.


Fluorite rough

One of the first people to observe fluorescence in minerals was George Gabriel Stokes in 1852. He noted the ability of Fluorite to produce a blue glow and named the phenomenon fluorescence. Although blue is the most common color to fluoresce in Fluorite, it is also possible to see radiant reds, lively purples and deep greens glowing within the gem under UV light.

Shop Fluorite here.


Phosphorescence is the process in which the energy absorbed is released relatively slowly in the form of light. The term is used by experts to describe gemstones that appear to glow in the dark. This effect is similar to the process that makes luminous hands on a watch visible to help you tell the time when you wake in the middle of the night.

Unlike the relatively swift reactions in fluorescence (where the effect is seen immediately), phosphorescent gemstones store absorbed energy for a longer time and retain their luminosity from within. This means they continue to glow even after the light source has been removed. Gemstones that possess a strong fluorescence may continue to glow for several minutes after they are taken into the shade after being exposed to ultraviolet light.


Kunzite rough

Kunzite is possibly the most famous gemstone with strong phosphorescence. The highest quality Kunzite can have a magical glow of intense pinks and warm peach hues for several minutes after an ultraviolet light source is removed. Its luminous appearance makes it one of the most romantic and feminine gemstones on the planet.

Shop Kunzite here.


Asterism Aventurescence Chatoyancy Labradorescence Polymorphism Tenebrescence Twinning

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