Feature Gems & Gemology, Spring 2003, Volume 39, No. 1

The First Transparent Faceted Grandidierite, from Sri Lanka

Gemological, chemical, and spectroscopic properties are presented for the first known transparent faceted grandidierite. This jewelry-quality 0.29 ct stone was fashioned from rough reportedly found in the Kolonne area of Sri Lanka. The greenish blue borosilicate has refractive indices of 1.583 to 1.622, which correlate to a low iron content of 1.71 wt.%  FeO and readily separate it from the gem material closest in properties, lazulite.