UV Fluorescence Testing

← Back to Testing Methods

Overview

UV fluorescence reveals how gemstones react to ultraviolet light. Many gems glow specific colors under UV, which aids identification and can indicate treatments or synthetic origin.

How It Works

Gems are exposed to longwave (365nm) and shortwave (254nm) UV light in a dark environment. Trace elements cause the gem to emit visible light (fluorescence) in characteristic colors.

Equipment Needed

  • UV lamp (longwave and shortwave)
  • Dark viewing cabinet
  • UV-protective eyewear
  • White background

Procedure

  1. Place gem on white background in UV cabinet
  2. Dark-adapt your eyes for 30 seconds
  3. Observe under longwave UV first
  4. Then observe under shortwave UV
  5. Note color, intensity, and distribution of fluorescence
  6. Check for phosphorescence after UV is turned off

Typical Values / Results

Gemstone Value / Observation
Diamond Blue (common), yellow, white, none
Ruby Strong red (Burmese), weak to none (Thai)
Emerald Usually inert (natural), red (some synthetics)
Kunzite Strong orange-pink
Fluorite Blue, violet (often strong)

Limitations

Fluorescence varies within gem species. Some treatments affect fluorescence. Never look directly at UV light without protection.