Black Tourmaline in Muscovite Plain Round Beads have a vitreous to pearly luster, show deep hues of black yellow ochre, cream, and olive green on their opaque bodies. These gems are lighter in weight than standard Black Tourmaline due to the addition of Muscovite. Muscovite is the most common mineral of the mica family  and these gemstones present with internal characteristics that create a lovely shimmer. 1mm inside diameter drill holes