This structure and the chemical composition of the gem give it remarkable properties. For example, some stones (like Alexandrite) display different colors depending on the light source under which you observe them; others, like Tourmaline, become electrically charged when heated and then cooled (this is called pyroelectricity); some, like Andalusite, show different colors depending on the angle from which you view the stone (this phenomenon is called pleochroism),…
Many other equally fascinating phenomena are created by these physico-chemical properties without being observable.