Variegated beads look better in larger sizes as small beads tend to become one color. Translucent beads are usually lighter in the small sizes. Organic beads and Chinese turquoise vary most in size as they are cut to maximize yield. Quartz is prone to fissures and chips at boreholes. Some are organic, were living at some time, such as mother of pearl or bone.
All obsidians are volcanic glass and goldstone is manufactured glass.