Star diopside is a type of calcium magnesium silicate with the chemical formula CaMgSi2O6. One of the interesting properties of this mineral is that it can exhibit asterism, which means when cut properly, a four-pointed star can be seen to float across the surface of the stone when it is moved under a direct light source. This effect is caused by the reflections from needle-like inclusions within the stone, typically from minerals like magnetite. It is worth noting that the four-rayed star is relatively uncommon in the gem world, with the most commonly known asterism being the six-rayed star seen in star sapphires and star rubies. Star diopside is often used in jewelry as a cabochon, the shape and polish that best reveals its star effect.
