Lab Notes Gems & Gemology, Fall 2017, Vol. 53, No. 3

Emerald with Mobile Inclusion

Rough emerald with mobile inclusion.
This 9.02 g rough emerald contains a prominent eye-visible mobile inclusion. Photo by Robison McMurtry.

Multiphase inclusions are key indicators when identifying emeralds and determining their origin. Gemologists look for the jagged three-phase inclusions in stones of Colombian origin or blocky two-phase inclusions in Brazilian or Zambian emerald. These multi­phase inclusions typically require higher magnification and considerable maneuvering of the emerald to get a precise view. 

Recently, the Carlsbad laboratory received a 9.02 g rough emerald from Lucas Fassari (Costa Mesa, California). The rough had an eye-visible mobile inclusion (see above) consisting of a CO2 gas bubble and salt crystals suspended in a fluid. The emerald was identified using a handheld spectroscope and optical properties. It was determined to be of Colombian origin by its jagged three-phase inclusions and crystals that had characteristics of pyrite and calcite. The mobile inclusion was quite large in relation to the rough emerald, which measured 28.76 × 14.82 × 12.83 mm, including its calcite and shale matrix. The CO2 bubble measured approximately 4 × 3 mm. 

Mobile inclusions of this size are captivating to observe, and to see one in an emerald adds more allure to the piece. Cutting this specimen into a faceted gemstone would lose what makes this rough emerald unique.

Nicole Ahline is a staff gemologist at GIA in Carlsbad, California.