Sunlight - known as “white light” - corresponds to a series of different lights that can be obtained through an optical prism. These lights are the colours of the rainbow and each of them has a different wavelength.
Our eyes can identify the wavelength corresponding to the colours red, orange, yellow, green, blue, indigo and violet. For example, the leaves of a tree absorb most of the light emitted by the sun, except one. This wavelength is reflected to our eyes and we identify it as being green. Thus the colours we see in daylight are reflected colours.
Fluorescence is not a reflection of ultra-violet lamp rays. Fluorescent colours come from the mineral itself. They depend on its physical structure and on its chemical composition.
When it reaches the mineral, the energy of the ultra-violet ray displaces electrons. This movement releases electric and magnetic energy and is characterized by a ray of light. The phenomenon is instantaneous.
Fluorescence is often due to the presence of impurities, known as activators, in the mineral. These activators, such as manganese, copper, lead, silver, uranium, rare earths and water molecules, produce different colours. Futhermore, the great majority of fluorescent minerals only react to a particular ultraviolet range. Fluorescence depends not only on the mineral itself, but also on the lamp used - long waves or short waves.