Description: Coarse diamond burr used for Sanding and forming. -Fine diamond burr used for sanding scratches and polishing. -if you want to end up with a 12mm bead , choose a 13mm coarse diamond burr and a 12mm fine diamond bur. -Ideal for grinding, shaping and polishing of Jade, amber, beeswax, turquoise and soft jade(Mohs hardness of below 6.5).et Specification: Name:polishing bits Shank: 4mm -5mm Rounding Size: inner size 5mm-25mm Grit Number: 320# Color:silver Material: Diamond Head shape: cylinder with concave surface. Quantity:1PC Package: 1pc polishing bit Note: 1. The real color of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness. 2. Please allow slight manual measurement deviation for the data. Made of high quality material, durable and practical to use. Perfect functions,give you a wonderful experience. We will ship it ASAP,when you place the order. If you have any questions, please feel free to contact us, we will solve it for you. Every customer can enjoy 30 days refund or replacement for Damaged/Quality Issues.