- > Gems & Jewellery
- > Journal of Gemmology
- > Ordering Back Issues of the Journal
- > Samples
- > The Journal online
- > Issues 2008 to date
- > Schmetzer, 2010
- > Volume 31, Nos 1-2, 2008
- > Li Jianjun et al 2010
- > Sturman Teaching
- > Sturman and Parker optic sign
- > Sturman and Parker shadow edges
- > Schmetzer, Chrysoberyl, 2011
- > Andersson, Maxixe beryl, 2011
- > Schmetzer trapiche tourmaline
- > Duroc Danner
- > Schmetzer Lake Manyara
- > Pearson Ultraviolet sources
- > Ostrooumov and Morales 2010 (1)
- > Bidney et al., 2010
- > Kitawaki et al., 2010
- > Hänni et al., 2010
- > Volume 31, Nos 5-8, 2009
- > Hainschwang 2010
- > Vol. 31, Nos 3-4, 2008
- > Cowing, 2010
- > Issues prior to 2008
- > Submitting Articles for the Journal
- > Direct Subscribers
Measurement and interpretation of growth patterns in chrysoberyl, including alexandrite
Dr Karl Schmetzer 
Abstract: Procedures for identifying growth planes, growth zones and twin planes in optical biaxial gemstones are described and the most commonly observed interfacial angles are tabulated, using chrysoberyl as an example. The strong pleochroism of the chromium-bearing chrysoberyl variety alexandrite was found to be a useful indicator for locating the positions of the crystallographic axes, and the optic axes are determined using interference fi gures
under crossed polarizers. Examples of the typical features of growth zoning in natural alexandrites from Russia, Sri Lanka and Brazil are shown. Twinned chrysoberyls from Madagascar are described in detail.
All the Journal articles placed online in 2011 will also be published in hard copy as a single Journal issue and sent to all paid-up Gem-A members early in 2012 as part of their 2011 subscription. Gem-A members may login to the membership area to view the full articles.