Micro-World Gems & Gemology, Summer 2016, Vol. 52, No. 2

Garnet Inclusion Illusion

Quartz cabochon with garnet “inclusion”
Figure 1. At first glance, this 42.88 ct quartz double cabochon measuring 28 × 18.5 × 15 mm resembles a beautiful garnet-included quartz gem. Photo by Elise A. Skalwold, from the Si and Ann Frazier Collection.

A cleverly designed “garnet in quartz” double cabochon represents a new and unexpected challenge for gemologists, collectors, and designers who intend to feature inclusion gemstones in their jewelry lines. This assembled inclusion consists of a fragment of pyralspite-series garnet sandwiched between two quartz cabochons (figure 1). The garnet and quartz were identified with optical and Raman spectroscopy, respectively, at GIA’s Carlsbad laboratory. While the specimen creates the illusion of being natural, clues to its artificial origin include air bubbles and the fragment itself, which shows neither crystal faces nor the rounded appearance of an etched or eroded crystal. Rather, it is a relatively sharp fragment that resides in a pocket filled with glue (figure 2). The subtle glue layer between the cabochons becomes more apparent when viewed under UV light, which causes it to fluoresce chalky white; this fluorescence is stronger under long-wave than short-wave UV.

Gas bubbles surrounding garnet
Figure 2. Gas bubbles can be seen in an otherwise nearly invisible glue layer between the quartz cabochons; these bubbles are abundant in the vicinity of the red garnet fragment. The fragment resides in a hollowed-out pocket and is surrounded with glue. Photomicrograph by Nathan Renfro; field of view 10.28 mm.

This specimen was purchased at the 2016 Tucson shows from a dealer specializing in inclusion specimens. The cabochon, part a collection of otherwise natural items, was fully disclosed as a man-made novelty. Its appearance in the marketplace represents an emerging trend that gemologists and collectors will see with increasing regularity as the fascination with inclusions grows (see the author’s forthcoming article, “Evolution of the inclusion illusion,” in the Summer 2016 InColor). Careful inspection with a loupe or microscope will in most cases reveal the underlying nature of this inclusion.

Elise A. Skalwold, an accredited senior gemologist of the Accredited Gemologists Association (AGA), is involved in curating and research at Cornell University in Ithaca, New York.