Other gemstones that may display asterism are rose quartz, garnet, diopside, moonstone, spinel and opal.
|Star rubies and star sapphires display a six-ray star that seems to glide 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. Fine star rubies and sapphire come mainly from Mogok and Sri Lanka. The best stones will have just enough silk to create the star effect, but not so much as to harm the transparency and color. These stones are rare and valuable.
|Black Star Sapphires with golden stars are one of the most fascinating forms of sapphire. The most valuable of the golden-star black stars come from Chanthaburi, Thailand.|
Black star sapphires differ from other colours of star sapphires because the star is formed not due to rutile silk but due to hematite plates.
|Star of Asia A round six-ray star sapphire weighing 329.7 carats. The stone's origin is Burma, and it's also part of the Smithsonian Museum's collection.
Weighing 27.62 carats, the Star of Bharany Ruby is one of the world’s finest star rubies.
|A star ruby is considered potent protection against magic. Star rubies were worn by knights in battle to protect themselves from the enemy. Tales in Karnataka (India) say that if it is worn as a visible pendant or as a headgear then anyone who faces you as an enemy loses half their valour. |
The power of star ruby is said to be the highest during full moon.