Star spinel 2,25 ct.

Star spinel.
Weight: 2,25 ct.
Measurements: 9,19 × 7,15 mm.
Origin: Sri Lanka, Ratnapura district.
Treatment: None.
2,25 ct dark dark purple star spinel. Big clear six rayed star in this clear (glassbody) dark purple spinel.
This rare optical phenomenon is called asterism, which is a star like pattern that forms on the surface of a gemstone when light strikes. Any gem exhibiting a good asterism is considered prized, and spinel is considered particularly rare.