Information Diamond processing types on drill bits include sintering, electric plating or brazing. Electroplated and brazed diamond is surface coated, attached to the surface of the cutting edge. The cutting edge is instantly aging when the diamond breaks off. Sintered diamond cutting edge contains diamond particles from inside to outside, to ensure that the edge is always sharp. Sintered diamond has the sharpening property but electroplated or brazed diamond can not be sharpened. Diamond Drill Bits Produce clean and accurate holes in minutes with little or no chipping. The pilot bit in the center helps for cutting accurate holes. Long Service life White zinc plating on the bits for good resistance to corrosion. Excellent for making holes on glass or ceramic and considerably extending drill bit life. Clearance Hole Diamond drill bits with clearance hole facilitate the entrance of cooling water and escape of chips and other particles from drilling. Makes drilling process get easier Start your hole diagonally, make a round trace and then hold drill straight. Please always use lubrication (water) when drill bits are working. Low drill pressure and increased use of water lubrication will extend drill bit life. Not suited for use on concrete or for depths beyond about 1/2 inch.