This article discusses the use of handheld long-wave ultraviolet torches with the microscope. It has been found that these have tremendous utility in identifying and characterizing certain oiled gemstones, such as emerald, tourmaline, etc.
When a red spinel and a tanzanite were submitted for testing, oil was found in the fissures. Removal of the oil resulted in a startling deterioration in clarity.
A truth that's told with bad intent, beats all the lies you can invent.
—William Blake [1757–1827], Proverbs, Line 95
