The black inspection tube is made of blue-black glass, and the inner tube wall is coated with phosphor. Radiation is converted to visible light, the so-called fluorescence effect, so they are suitable for all applications involving fluorescence analysis." When used in the dark, these tubes or lamps emit a mixture of UVA and visible light, resulting in the popular glowing luminous bluish/purple color. The most common applications for blacklight blue tubes are: Party lighting - Because of their glowing properties, these popular lights are frequently used at nightclubs or paint parties. Detecting discrepancies in banking - Banks use blacklight blue tubes  to detect fake money. UV nail lamps - These are used at salons and can also be purchased for home use.