Tales of Tolgard
Also known as iolite, cordierite, or violet stone (despite its usual overall hue of blue), this semiprecious stone is usually cut into faceted gemstones to best display its color change when viewed from different directions. Iols so viewed appear straw-yellow, blue, and dark blue. Small, cut iols can be clear, but larger specimens usually contain silky inclusions of another substance that gives them an internal star effect or even trapped hematite crystals, which give the same rich golden flash of color as is found in sunstones. Iols have strong associations with magic in legends, but few folk know their true magical use: They are the best sort of gemstone to transform (with the proper, secret spells) into ioun stones.