The objective of this research is to study characteristics of Ruby from Kilindi Deposits in Tanzania, which is the new gem deposit of the country and trends to be highly exported. Basic and advanced gem-testing instruments based at The Gem and Jewelry Institute of Thailand were used for this study. The main aim of this study is to develop database for further investigation of ruby’s origin. The origin of ruby from Kilindi is from Amphibolite rock, which is located on the Usagaran system in association with East African Rift System. Twenty six ruby samples under this study are opaque with obvious internal cracks and crystal inclusions. Their luminescences are weak under long wave and inert under short wave UV lamps. Mineral inclusions are identified as rutile, amphibole, zircon, chromite, garnet, and chlorite. In addition, various types of inclusions such as fracture, growth line, and fingerprint are often found. Based on advanced analyses, strong absorptions of chromium and iron under UV-Vis-NIR are clearly observed. For absorption under Infrared, Kilindi rubies usually show absorption of OH group at 3090, 3320, 3630 and 3700 cm-1. Furthermore, trace element analyses contain relatively high contents of Fe₂O₃ and Cr₂O₃. Proportional plots between Cr₂O₃/Ga₂O₃ and Fe₂O₃/TiO₂ show trend of metamorphic origin; in addition, from other deposits plots of V, Fe and Ga also show the distinctive proportion of ruby from Kilindi.
