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

Helical Inclusion in Colombian Emerald

A three-dimensional helical inclusion in emerald.
A three-dimensional helical inclusion in emerald. Photomicrograph by Taku Okada; field of view 2.93 mm.

GIA’s Tokyo laboratory recently examined a 7.54 ct natural emerald containing a 3D helical inclusion (see above) resembling a DNA double helix or fish bone. This helix, consisting of whitish grains, reached the emerald’s surface. The other associated inclusions were jagged three-phase fingerprints, growth tubes, and the gota de aceite optical effect (R. Ringsrud, “Gota de aceite: Nomenclature for the finest Colombian emeralds,” Fall 2008 G&G, pp. 242–245). All these features supported a Colombian origin. To date, three emeralds examined in GIA’s Tokyo laboratory that were reportedly Colombian have exhibited similar inclusions. This helical inclusion may therefore be a characteristic of Colombian emeralds. Such a discovery within a stone is always pleasing.

Taku Okada is a staff gemologist at GIA in Tokyo. Piradee Siritheerakul is manager of identification at GIA in Bangkok.