Blue Kyanite Sterling Silver Ring Black Tourmaline the fourth stone

the fourth stone

The mineral's name comes from the Greek apatao (to deceive)—it was historically mistaken for Tourmaline

and a genuinely piezoelectric and pyroelectric mineral: it generates an electric charge under mechanical pressure and temperature change

and Roman signet rings frequently used garnet inlay

Among the oldest documented gemstones

Blue Kyanite Sterling Silver Ring Black Tourmaline the fourth stoneA blade of blue caught in silverthe mineral's natural striations visible through the stone. Blue Kyanite is an aluminum silicate, chemical formula Al2SiO5, with a distinctive anisotropic hardness: Mohs 4. 5 along the long axis, Mohs 6. 5 across itwhich is why lapidaries work it with such care. Its color ranges from pale sky to deep sapphire, concentrated in parallel striated bands that run the length of each blade shaped crystal. This faceted stone is