Sapphire Inclusion with Rutile “Silk” in a Burmese Star Sapphire
GIA’s Hong Kong laboratory recently examined a remarkable sapphire inclusion inside a Burmese star sapphire. Possessing the same refractive index as its host, the sapphire guest displays extremely low relief and is nearly invisible under transmitted light. Nevertheless, its outline became distinctive under cross-polarized illumination, showing strong interference colors (see above, left). Closer examination using fiber-optic illumination revealed a group of oriented rutile “silk” in this sapphire inclusion (see above, right). Although exsolved rutile needles are a common inclusion in Burmese sapphire, it is interesting to see two sets of dense silk exsolved from both the star sapphire host and a protogenetic sapphire inclusion, each aligned with the basal plane of its own host.