Tourmaline Inclusion with Included Crystals in Kashmir Sapphire

Yusuke Katsurada and Tyler Smith

The authors recently examined a 1.81 ct blue cushion mixed cut identified as sapphire. Microscopic examination showed sharp-banded milky clouds, particle stringers, and a well-formed euhedral greenish crystal. The crystal displayed a triangular prismatic habit with sharp basal pinacoids. This is typical of tourmaline, and the inclusion’s identity was later confirmed by Raman spectroscopy.

Tourmaline inclusions in sapphire are diagnostic of a Kashmir origin (see R. Schwieger, “Diagnostic features and heat treatment of Kashmir sapphires,” Winter 1990 G&G, pp. 267–280). Trace element analysis with laser ablation–inductively coupled plasma–mass spectrometry supported the microscopic observations, revealing a chemistry consistent with classic Kashmir samples from GIA’s colored stone reference collection.

Interestingly, the tourmaline possessed uneven rounded inclusions of its own (see above). These crystals were presumably a different material, given their lighter tone and sharp boundaries, which contrasted with the tourmaline host. Unfortunately, they could not be identified with Raman spectroscopy, leaving us to speculate about their true nature.