Star garnet
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Star garnets are a special form of the gemstone garnet. While colored like other garnets (predominantly red though other colors exist) they display a reflection-like image of a four or six pointed star caused by the inclusion of rutile needles, oriented at 70 and 110 degrees. The star garnet is Idaho's state gem. The star form of garnet is relatively rare, occurring in quantity only in Idaho and India. The six pointed star garnets are only found in Idaho.
The Star sapphire is another gem that displays a similar asterism.