Garnet comes in almost every color, but collectors continue the quest for stones showing a blue hue. This goal seemed within reach in the late 1990s, with the discovery of "blue" color-change pyrope-spessartine from Bekily, Madagascar. These stones commonly appear blue-green in daylight and purple in incandescent light (see "Garnets from Madagascar ...," Winter 1999 Gems & Gemology, pp. 196–201). Yet only a few well-formed garnet crystals have been reported from Bekily (see Summer 2003 GNI, p. 156); most are irregularly formed fragments.

Resembling color-change garnet from Bekily, Madagascar, this approximately 1 centimeter fluorite is violetish blue in daylight (left) and purplish pink in incandescent light (right). Photos by Robert Weldon.

Therefore, one of us (JH) was quite excited about the prospect of documenting a relatively large (1.1 × 1.0 × 0.9 cm) well-formed crystal thought to be blue garnet from Madagascar. The gem-quality sample was seen at the 2008 Tucson gem show and loaned by Jasun and Mandy McAvoy of Asbury Park, New Jersey. Its crystal form was similar to the previously published specimens of pyrope-spessartine from Madagascar, and it displayed a color change from violetish blue to purplish pink (see figure).

Although the crystal's form, isotropic optic character and color-change behavior were consistent with garnet, Raman analysis by Karen Chadwick at the GIA Laboratory proved that it was actually fluorite. This was quite a surprise to all involved with this specimen, which apparently had never before been tested. In hindsight, the crystal was remarkably similar—in its modified cubic crystal form and color—to some of the color-change Ethiopian fluorites documented in the Summer 2007 GNI (pp. 168–169).

Jim Houran
Mineralogical Association of Dallas

Brendan M. Laurs