Diamond Halo Beads - Gunmetal. These diamond shaped Halo beads are designed to quickly and easily bezel around 2-hole DiamonDuos and most GemDuo glass beads. You can also use these Halos as spacers for a unique look in your jewelry design. Give your jewelry a modern edge with the sharp look of premium Zamak metal. The Potomax Halo beads for diamond shapes feature 4 holes and measure 7.5x10.6mm with a 5x8mm center. They come in a pack of 10.