Many gemstones are particularly vulnerable to environmental factors that can impact their visual appeal and structural integrity. One such factor is ultraviolet (UV) light, producing both both positive and negative effects on gemstones, depending on their properties and the intensity and duration of exposure.

The key adverse effect of UV light is colour fading or alteration, particularly for gemstones that have undergone treatment or enhancement. Varieties of untreated quartz and corundum can start to loose their colour quickly when exposed to extensive sunlight. Heat-treated or irradiated gemstones such as sapphire and topaz are also particularly susceptible to colour fading. Additionally, certain types of pearls can lose their lustre and become dull under prolonged UV light exposure.

UV light can also have beneficial effects on some gemstones. Certain gemstones, including diamonds and specific sapphires, exhibit fluorescence when exposed to UV light, leading to enhanced vibrancy and colourfulness.
It should be noted that UV light is not the only environmental factor that poses a risk to gemstones. Heat, moisture, and chemicals are other factors that can compromise the physical and visual qualities of gemstones. Therefore, proper maintenance and care are crucial to ensuring their longevity and aesthetic appeal.