Micro-World Gems & Gemology, Summer 2019, Vol. 55, No. 2

Purple Fluorite Inclusion in Emerald from Russia

Purple fluorite inclusion in a Russian emerald.
A Russian emerald hosts a crystal inclusion—identified by laser Raman microspectrometry analysis as fluorite—that exhibits a distinct purple color. Photomicrograph by Jonathan Muyal; field of view 1.44 mm.

Fluorite inclusions in emeralds from various localities have been reported extensively in the literature. They have been described as “whitish-colorless, octahedral-cube and/or corroded rounded shapes” (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 3, Opinio Publishers, Basel, Switzerland, 2008). However, purple fluorite in an emerald host is rare.

Author CM previously documented a purple banded fluorite inclusion in an emerald submitted to GIA for identification (Fall 2016 Lab Notes, pp. 302–303). This was noted as “an interesting and unexpected addition to an otherwise typical (emerald) inclusion scene.” Surprisingly, the current authors recently found another purple fluorite inclusion in an emerald (see above) from GIA’s research reference collection. Purchased from Alexey Burlakov (Tsarina Jewels, JTC, Bangkok), it was reportedly from the Malysheva mine, located a few kilometers northeast of Yekaterinburg, Russia.

Closer examination of the inclusion revealed a large, distinct purple zone, as well as a purple band and a subhedral crystal form. The inclusion proved to be singly refractive when viewed between crossed polarizers. Laser Raman microspectrometry confirmed that the inclusion was fluorite. Trace-element chemistry of the host emerald collected via laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) matched well with GIA’s Russian emerald chemistry reference data.

Raman analysis and microscopic observation conclusively identified the inclusion as fluorite. This strongly suggests that the unusual purple inclusion observed by author CM in 2016 was indeed fluorite; in that case, the inclusion was too deep in the stone to analyze with Raman. It is possible that purple fluorite is an unusual internal feature found only in Russian emerald, since that is the only known source from which we have observed this inclusion.

Jonathan Muyal is a staff gemologist, and Claire Malaquias is a gemology specialist, at GIA in Carlsbad, California.