Tsavorite Dr. Campbell R. Bridges dicovered this gem in 1967 ( he was murdered in 2009 after a long dispute over access and mining rights with local tribes)
Named after the first location that this gem was found in the Tsavo National Park in Kenya. The only other known source for this gem is in madagascar. The colour is caused by Trace amounts of vanadium or chromium that provide the green color.
It has a Mohs scale hardness 7 - 7.5
It is singulary refractive Refractive index 1.740
Unlike many other gemstones, the tsavorite is neither burnt nor oiled.
Only in rare individual cases is a raw crystal of over 5 carats found, so a cut tsavorite of more than two carats is a rare and precious thing