Other Star Gemstones
This collection gathers star stones other than ruby and sapphire, such as black star diopside (CaMgSi2O6) and star garnet. Like all star stones, they show asterism: a star of light that glides across a cabochon under a single light, caused by fine needle-like inclusions aligned inside the crystal.
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Gemstone guide
Other Star Gemstones
About other star gemstones
Asterism appears in several gem species. Black star diopside, mostly from India, shows a four-rayed star from needles of magnetite, which also make it slightly magnetic. Star garnet, found mainly in Idaho in the United States and in India, usually shows a four- or six-rayed star on a dark purplish body. These stones are generally untreated and are among the most affordable natural star stones.
What you'll find in this collection
This collection mainly holds untreated black star diopside, listed with an African origin, in oval and round cabochons from about 2.3 to 4 carats, each photographed under a single light to show the star.
How to recognise these star stones
Black star diopside shows a four-rayed star, often with two sharp and two softer rays crossing at an angle, and a strong magnet will pull on it. Star garnet is singly refractive and its rays meet at slightly different angles than in corundum. In all of them, the star should move smoothly as the stone tilts under a single light.
Caring for these star stones
Diopside is softer than corundum, with a Mohs hardness of 5.5 to 6 and two cleavage directions, so protect it from knocks. Clean these stones with warm soapy water and a soft brush, and avoid ultrasonic cleaners.
Every stone is natural, and each listing gives its weight, size, origin and treatment, with photos of the actual stone.