This Spanish treasure is undeniably one of the most highly pleochoric gems created by nature.
Andalusite is a transparent to translucent gem that derives its name from Andalusia in Spain where it was first discovered.
The gem is actually a polymorph of two gem varieties: Sillimanite and the hugely popular Kyanite. This means they are identical in chemical composition but differ in crystal structure.
Andalusite is often mistaken for Smokey Quartz, Chrysoberyl or Tourmaline. The gemstone benefits from a very distinct and attractive pleochroism, which lapidarists try to highlight when faceting the gem. Usually, when cutting strongly pleochroic gemstones (Iolite, Tanzanite, Kunzite, etc.), lapidarists typically try to minimize the pleochroism and maximize the single most attractive colour. Interestingly, Andalusite is the opposite, as all the colours visible in different directions are attractive. Cutters therefore try to orient the gem to get a pleasing mix of its orange, brown, yellow, green and golden colours. When cut successfully, Andalusite looks unlike any other gemstone, displaying patterns of colour dancing around its facets
Andalusite registers 7.5 on the Mohs scale, and in addition to Spain has been discovered in Switzerland, Sri Lanka, Kenya, Mozambique and the USA.