Standard gemological testing gave a spot RI reading of 1.43 and a hydrostatically calculated SG of 2.10. When exposed to ultraviolet radiation, the stone fluoresced strong bluish white under long-wave and weak bluish white under short-wave UV. It phosphoresced green after exposure to long-wave UV. Advanced gemological testing by energy-dispersive X-ray fluorescence (EDXRF) confirmed a silica-rich material with some additional trace elements, including aluminum and iron. All of these properties were consistent with opal.
Microscopic examination revealed large parallel planes with play-of-color intersecting to form a hexagonal pattern (figure 2). This is responsible for producing the six-rayed star. This unusual stone serves as a reminder that, unlike asterism in other gem materials, the star in opal is caused by diffraction of light from faults or imperfections in the packing arrangement of silica spheres.
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