Specifications:Head Diameter: 30mm / 1.18" (spherical diameter is about 1mm-1.5mm smaller than the head diameter.)Shank Diameter: 6mm / 0.24"Shank Length: 22mm / 0.87"Overall Length: 45mm / 1.77"Grits: 100 (fine grit)Head Shape: Spherical, Concave (the concave arc is smaller than a semicircle.)Material: Diamond, Carbon SteelPackage Included: 1pcs x Diamond Mounted PointDescriptions:Electroplated diamond has high hardness and good wear resistance. Chamfered round shank provides easier clamping and stable working process.Suitable for polishing jade, amber, stone, beeswax, glass etc. Specially used for forming and grinding spherical bead. Produce clean and accurate spherical beads in minutes with little or no chipping. Always use lubricant (water or cutting fluid) to cool the workpiece when the grinding bit is working.