About Ultraviolet induced Fluorescence

Fluorescence is the emission of light by a substance that has absorbed ultraviolet radiation.  Many substances will glow (fluoresce) with colored visible light. The color of the light emitted depends on the chemical composition of the substance.   From https://en.wikipedia.org/wiki/Fluorescence

When a UV photon strikes an atom in a mineral, it provides energy that excites an electron, causing it to jump to a higher energy level. After a brief moment, the excited electron returns to its original position and releases a photon of its own. This emitted light often has a longer wavelength than the original UV light, which we perceive as fluorescence.