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Phosphorescence is luminescence that continues after the source of excitation has been removed. In gemology, a gemstone may briefly glow after exposure to ultraviolet (UV) light because some absorbed energy is released gradually rather than immediately.
What Does Phosphorescence Mean in Gemology?
Phosphorescence differs from fluorescence mainly in persistence. Fluorescence generally ends quickly when the UV source is switched off, while phosphorescence can remain visible for seconds or longer, depending on the material and testing conditions.
How Phosphorescence Appears in a Gemstone
After UV exposure, a gem may show a fading blue, green, orange, or other glow. The color, brightness, and duration depend on defects, impurities, excitation wavelength, exposure time, and the gemstone itself. Many gemstones show no visible afterglow.
Why Phosphorescence Matters in Diamond and Gem Evaluation
Phosphorescence is a useful supporting observation in some diamond and gemstone examinations. Certain diamonds can show notable afterglow, but its presence or absence is not conclusive proof of natural or laboratory-grown origin, treatment status, or value.
How Gemologists Observe or Test Phosphorescence
A gemologist exposes the stone to an appropriate UV source, switches the light off, and observes whether emission continues. The result may be recorded by color, strength, and duration under controlled conditions. UV safety precautions and other identification tests remain important.
Related Gemology Terms
- Luminescence: Light emitted after a material absorbs energy.
- Fluorescence: Luminescence that generally fades rapidly when excitation ends.
- UV Reaction: A gem’s response to ultraviolet light.
Explore the Custom Karat Jewelry Glossary and Advanced Gemology & Diamond Optics for more related terms.
About Author Priyanka Kale
Priyanka Kale is a jewelry retail industry author who shares knowledge on diamonds, lab-grown jewelry, custom designs, and jewelry buying tips. Her content helps customers understand quality, pricing, trends, and craftsmanship before making confident jewelry purchase decisions.
