Calcite can also exhibit pronounced pink to red fluorescence. Therefore, it can be said that fluorescence as a single tool of identification is unreliable. Furthermore, synthetic rubies exhibit a stronger fluorescence than natural stones. This may be due to the presence of traces of iron. For example, Siamese ruby has a weaker fluorescence than Burmese ruby. Rubies from some sources show a stronger fluorescence than gems from other locations.

The fluorescence of ruby can be seen somewhat in daylight, since daylight contains some UV light, but to properly appreciate the fluorescence of ruby, artificial UV light is best. When it comes to fluorescent gemstones, ruby is the best-known gemstone that exhibits red fluorescence. In the Crystal Caves of Australia, the owner has taken this idea even further and has an incredible display of mineral orbs that appear like an 'alien galaxy' fluorescing in all the colors of the rainbow. Since UV light is not visible to the human eye, the fluorescing materials appear to magically glow in the dark, so these minerals are an amazing spectacle to see. Also, there can be a difference under short-wave and long-wave UV light. The fluorescence of minerals may be absent, weak or strong, and may vary in color depending on the specimen. In the mineral galleries of museums and other such exhibitions, there is often a display of fluorescent minerals where the minerals are lit by an ultraviolet ('UV' or 'black') light so that their fluorescence is shown. The magic can be seen when these materials are placed in a dark area under fluorescent light. Fluorescent minerals look quite ordinary until ultraviolet light is shone on them, and then they come to life. For example, a famous blue diamond known as the Hope Diamond fluoresces red. A gemstone can sometimes be distinguished by the color that it fluoresces. Fluorescence is, therefore, a useful tool when it comes to identifying certain gemstones.

This means that they emit visible light after being exposed to light of a shorter wavelength, typically ultraviolet light. Have you ever noticed that in some light, for example in a dark nightclub, your teeth and other white things seem to be really bright and glowing? This is because ultraviolet light is absorbed and then the energy is emitted as visible light. A Ruby under Daylight (Top) and UV Light (Bottom)

Blue gems list