Feature Gems & Gemology, Winter 1996, Volume 32, No. 4

Trapiche Rubies

Ruby crystals from Southeast Asia with a fixed six-rayed star, similar in effect to trapiche emeralds from Colombia, are described. They consist of six transparent-to-translucent ruby sectors separated by nontransparent yellow or white planes. Most samples also have a hexagonal tapered yellow, black, or red core. In the yellow or white arms of the star and in the boundary zones between the core and the six ruby sectors, a massive concentration of tube-like inclusions is seen. These inclusions are oriented perpendicular to the morphologically dominant dipyramidal crystal faces; they contain liquid, two-phase (liquid/gas), and solid fillings identified as magnesium-bearing calcite and dolomite. A trapiche-type sapphire is also described.