https://www.gia.edu/CN/gems-gemology/spring-2013-gemnews-dumortierite-quartz-rock-sapphire
Dumortierite-Quartz Rock Presented as Sapphire | Gems & Gemology
The Gem Testing Laboratory of Jaipur, India, received for identification an opaque blue specimen, submitted as sapphire.
dumortierite quartzsapphire gemsrockpresentedgemology