Half-drilled beads and pendants are usuallly used with glue-in bails, ear studs or finger rings with glue-in pins. While regular glass pearls have 2-4 color layers (up to 7 layers for high quality pearls), Nacre Pearls from from Preciosa have at least 12! This creates almost magical luster. The proces is very similar to natural forming of genuine pearls.