Micro-World Gems & Gemology, Spring 2021, Vol. 57, No. 1

Thin-Film Fluid Inclusions in Aquamarine

Thin-film fluid inclusions in aquamarine display interference colors.
Thin-film fluid inclusions oriented perpendicular to the c-axis of this aquamarine display interference colors when viewed using oblique fiber-optic illumination. Photomicrograph by Muzdareefah Thudsanapbunya; field of view 2.79 mm.

The author recently examined a faceted aquamarine from Brazil that showed two-phase (liquid and gas) thin-film inclusions of different sizes and shapes. When observed using oblique fiber-optic illumination, the inclusions revealed a kaleidoscopic play of interference colors (see above). The most diagnostic beryl inclusions, yet barely noticeable in brightfield illumination are ultra-thin-film fluid inclusions. The planar surface of these inclusions is oriented parallel to the basal pinacoid of their host (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Volume 2, Opinio Publishers, Basel, Switzerland, 2005, pp. 312–314). The presence of the bright iridescent thin-film fluid inclusions resembles colorful rainbow sprinkles.

Muzdareefah Thudsanapbunya is an independent gemologist from Bangkok.