YAG with Flux-Filled Fingerprints
Flux-filled fractures displaying geometric shapes and iridescent colors when viewed through crossed polarizers. Photomicrograph by Michaela Stephan; field of view 2.9 mm.
The author recently examined a 3.58 ct yellowish green yttrium aluminum garnet, a manufactured product known in the trade as “YAG,” that contained numerous large flux-filled fractures. The flux material crystallized in the fractures formed interesting geometric shapes that showed birefringent interference colors when viewed between crossed polarizers, reminiscent of stained glass windows (see above). It is possible this YAG was intentionally fractured and filled with flux to more convincingly imitate tsavorite grossular garnet. Although the flux inclusions in this example were quite beautiful, such inclusions are not common in this manufactured gem material.
