Star Aquamarine
The Carlsbad laboratory recently received a grayish blue aquamarine for an identification report. The unique 13.37 ct oval double cabochon displayed a six-rayed star (figure 1). Standard gemological testing revealed a spot refractive index of 1.570 and a hydrostatic specific gravity of 2.68. Raman analysis confirmed that the stone was beryl.
Under magnification (figure 2), the stone displayed planes of negative crystals, film-like inclusions, ilmenite, and reflective particles that resulted in a six-rayed star. Asterism in aquamarine is due to three sets of elongated channel-like or thin-film inclusions oriented in three different directions perpendicular to the c-axis (e.g., Spring 2004 Gem News International, p. 104; K. Schmetzer et al., “Asterism in beryl, aquamarine, and emerald—an update,” Journal of Gemmology, Vol. 29, No. 2, 2004, pp. 66–71). Of all the aquamarines examined at GIA laboratories, this was one of the first to display asterism.
