Preciosa Art 3293 Rauten Cut Round flat back crystals are made of glass. These multi triangle faceted jewels are large and come to a pointed top. Available in Crystal and Crystal AB and a variety of colors, these stones come in graduating sizes from 7mm (SS34) up to 25mm (almost an inch). The Transparent colors are foiled on the back for extra shine and reflection. The jet, metallic colors and iris's colors are unfoiled but feature a high gloss shine. Not all sizes are available in all of the colors. The iris colors, like its name feature a center high light, please note variation may exist from the color of the stones to a purplish color, hence Iris..