Diamagnetic Gems and
Paramagnetic Gems

Diamagnetism
Diamagnetism is a form of magnetism where certain minerals are repelled by an externally applied magnetic field, and form internal induced magnetic fields in the direction opposite to that of the applied magnetic field, thus causing a repulsive effect. Consequently, diamagnetism is a form of magnetism that is only exhibited by a substance in the presence of an externally applied magnetic field. It is generally quite a weak effect in most materials, although superconductors exhibit a strong effect. Barite, Bismuth and Ludlamite are diamagnetic. Bismuth is the most naturally diamagnetic element and has one of the lowest values of thermal conductivity among metals.

Paramagnetism
Paramagnetism is a form of magnetism where certain minerals are attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. Xenotime is paramagnetic.

History
In 1778 S. J. Bergman was the first individual to observe that bismuth was repelled by magnetic fields. However, the term "diamagnetism" was coined by British scientist Michael Faraday in September 1845, when he realized that all materials in nature possessed some form of diamagnetic or paramagnetic response to an applied magnetic field. Paramagnetism was discovered and originally researched by Michael Faraday.