Analysing the Luminescence of Gems

Luminescence imaging and spectroscopy have become essential in gem testing, as most gem minerals and materials exhibit specific luminescence when properly excited. With a range of techniques introduced in gem testing laboratories in the past quarter century, such as luminescence imaging and photoluminescence (PL) emission and excitation spectroscopies, there are many applications to gem materials for establishing their identity, separating natural from synthetic gems, and detecting potential treatments. Further, these techniques often give clues towards the identity of emitting defects. Luminescence-based testing has recently gained attention even outside the gemmological laboratory as many simple luminescence-based instruments are offered to the gem and jewellery trade to separate natural from synthetic diamonds or from their imitations.