Madagascar's gemstone production boomed in the 1990s and has continued over the last decade. The mining region around the towns of Ilakaka and Sakaraha in the south central part of the country is the most prolific. The area is mined by a combination of traditional diggers and private investors, - some with machinery. Occasional alexandrites are found as a very small percentage of the alluvial mix. Although some gem quality large single chrysoberyl crystals up to 12.5 cm were recovered in the Lake Alaotra.

The gemstones present in the Ilakaka deposit are numerous, and include chrysoberyl, vivid yellow- green and of the cat's eye variety ; chrysoberyl of the alexandrite variety , in some cases with a very good metameric effect. Geological observations indicate that the gemstones of the Ilakaka region, are hosted in coarsegrained lenses of graywacke of the Permian-Mesozoic sedimentary sequence. The sequence ranges from Permian to middle Cretaceous in age, and consists mainly of sediments of continental origin. Sediments of mostly marine origin cap the sequence.