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Luminescence is light emitted by a gemstone after it absorbs energy from a source other than ordinary heating. In gemology, the term often describes a gemstone’s response to ultraviolet (UV) light and includes fluorescence and phosphorescence.
What Does Luminescence Mean in Gemology?
Some minerals contain defects or trace elements that absorb energy and then release part of it as visible light. The emitted color may differ from the stone’s appearance in daylight. Not all gemstones luminesce, and a response can vary even within the same gem species.
How Luminescence Appears in Gemstones
Fluorescence is visible during excitation and typically fades rapidly when the energy source is removed. Phosphorescence persists for a measurable period afterward. Depending on the material and test conditions, the glow may be blue, green, orange, red, or another color.
Why Luminescence Matters in Gem Evaluation
Luminescence can support identification, treatment investigation, or laboratory screening. Diamond fluorescence is sometimes described on grading reports, but fluorescence intensity by itself does not establish beauty, value, origin, or authenticity. The same visible response may occur in different materials.
How Gemologists Observe or Test Luminescence
Gemologists use controlled long-wave or short-wave UV sources and note the color, strength, distribution, and persistence of any glow. Observations should be made with appropriate UV eye and skin protection, then considered alongside other gemological evidence.
Related Gemology Terms
- Fluorescence: Light emission that usually ends quickly after excitation stops.
- Phosphorescence: Light emission that continues after the excitation source is removed.
- UV Reaction: A gemstone’s observable response to ultraviolet illumination.
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.
