CORDIERITE OR IOLITE
Often used in jewelry today, cordierite varies in color from violet-blue to pale yellow depending on the angle from which it is observed. Named after French geologist Pierre-Louis Cordier (1777-1861), this mineral is more commonly known as iolite, from the Greek Ion meaning violet and Lithos meaning stone. The blue of a cut cordierite is similar to that of certain sapphires, hence its misnomer, “water sapphire”, although it is now illegal to use this name. Silicate of magnesium and aluminum. Hardness: 7 to 7.5. Symbol of trust and security. Sri Lanka, Brazil, Madagascar.