These beads have a diameter of 6mm to 6.5mm and a dark green color palette with some variation in thickness. Fans of Idocrase will appreciate the rich hues on this popular and eye-catching faceted shape. Idocrase, also known as Vesuvianite, was named after Mount Vesuvius in Naples, Italy, by A. G. Werner in 1795. The gem-grade quality is called Idocrase.