Andalusite Gemstones

Andalusite is an attractive and unusual gemstone, first discovered in Andalucia, Southern Spain, after which it is named. It has some similarities with the very rare and valuable alexandrite, as it is strongly pleochroic, about which more later. It is suitable for use in jewelry as it is quite hard. The fact that it is seldom seen in jewelry is probably because it is quite rare, and most people, even in the jewelry industry, have never heard of it, let alone seen it. Strangely enough, some years ago we had just finished making a ring set with a central andalusite, when another local jeweler visited us.

Coloration
Many andalusites display different colors within the same stone. This is due to the phenomenon of pleochroism. Pleochroism is the differential selective absorption of the ordinary ray and the extraordinary ray in uniaxial stones (dichroism), or of the three rays corresponding to the three principal vibration directions in biaxial stones (trichroism).

For the non-gemologist, the above explanation may create more confusion than clarification. More simply, pleochroism relates to the way light is refracted when passing through a stone.

Typical colors for andalusite are green, brown, red, greenish-brown, brownish-green. Its pleochroic colors are red, green and yellow. Because of the pleochroism, the color of an andalusite can be affected considerably by the direction in which it is cut.

Sources
As noted above, andalusite was originally discovered in Andalucia. However, it is also found in Brazil, Sri Lanka (Ceylon), Siberia, Brittany, Australia and the United States. Small non-gem crystals are also found in Cumbria, United Kingdom.