Photoluminescence (PL) is the emission of light caused by irradiation with photons. The emitted light is usually of a longer wavelength, and has lower energy, than that of the absorbed radiation.
Both phosphorescence and fluorescence are forms of photoluminescence. Phospholuminescence persists for seconds or minutes after the illuminating source has been extinguished whereas the glow of fluorescence disappears almost immediately the illuminating source is extinguished.
Most gems exhibit a characteristic photoluminescence of visible light in response to ultra-violet irradiation. Gemmologists use both short-wave (255 nm) and long-wave (365 nm) to probe the reaction of gems and note the colour and intensity of fluorescence and phosphorescence.
Conventionally such PL systems are desk mounted, which can be limiting where portability is needed. The PL inspector provides the most compact short-wave (SW) and long-wave (LW) instrument. Coupled with an optional battery power pack it becomes a pocket travel unit, ideal for trade events - to identify, for example, if a diamond is synthetic or treated.
Click here to view a yellow diamond that shows blue fluorescence under ultra-violet light - and see how it is is possible to distinguish between a natural and synthetic diamond. For practical workshops on natural, treated and synthetic diamonds and how to use the PL-inspector and other portable instruments visit www.gemconference.com