Blue shortwave luminescence of gems: the role of titanate groups
The purpose of this study is to describe Blue Shortwave-UV excited Luminescence (BSL) in gems and related materials, and demonstrate the role of titanate groups in a number of gems
Purple to bluish grey chalcedony from Ethiopia
In the past 15 years, Ethiopia has repeatedly gained attention for a variety of new gem finds. In 2008, a large deposit of white play-of-colour opal was found (Rondeau et al., 2010
Opal stability: a step toward detection
Opal is a gem of captivating beauty that stems from its complex microscopic structure composed mainly of silica. In the most striking specimens, the light diffraction from a three-