 | Star rubies and star sapphires display a six-ray star that seems to glide magically across the surface of the gem when moved. This six-ray star is caused due to an optical phenomena known as "asterism".
The term is derived from the Greek word "aster", which means star, so asterism is commonly referred to as "star" or "star-effect". Other popular gemstones that display asterism are rose quartz, garnet, diopside, moonstone, spinel and opal. |  |