Dumortierite-2015-10
Dumortierite from Tanzania
Gem dumortierite from the Umba Valley in Tanzania, striking octagon cut 7.8 x 6.26 x 5.5 mm, 2.14 carats. (Photo: Mia Dixon)
Pala International is lucky to have a large body of gemologically oriented readers. We get mail daily with articles and new localities and offers of rare gemstones. Our featured gem this month comes from just such an enthusiastic reader. And it is offered here for sale: a rare gem-quality dumortierite of extraordinary color with a GIA certificate. Let this be a reminder to keep Pala in mind for exceptional rare gems that you all find along the path of collecting.
A simple rough purchase turns into potentially one of the rarest and largest of its kind. Fancy-colored sapphires are common in the Umba Valley, since rough has been mined and traded there for a long time. A gem dealer bought a few pieces of what were thought to be sapphire and to his surprise, after cutting and certification, one orange-pink piece turned out to be dumortierite. An anomaly amongst the sapphire fields in Umba, dumortierite is a more complex mineral of the neosilicate group. Dumortierite is defined by the chemical structure Al7O3-(BO3)(SiO4)3, and is most often found in gem-grade material as small included blue crystals. This extremely unique orange-pink hue is reminiscent of a padparadscha sapphire and is a one-of-a-kind piece.
Rough sapphire…? The unidentified dumortierite on the left before cutting, alongside actual sapphires.