Use the Groove Edge to create a groove around the outside of fused glass pieces, beads, stones, cabochons and more. Diamond Groove Jewelry Grinder Bit is used for shaping and grinding the edges of glass pieces and creating grooves in stained glass for wire wrapping. If you're a glass artist, these grinder bits are essential. We have a large variety of different grits available in sizes. All grinder bits are 1.4mm in thickness and come with a set-screw Allen wrench and square-shaped sponge to keep your glass piece cool while you work.