1mm Diamond Drill Bits - 20Pcs Diamonds Glass Jewellery Drilling Set Solid Bit Needle Twist Drill Bits for Jewelry, Agate, Ceramic, Jade

【High Quality Material】: These diamond drill bits are made of diamond powder, sturdy and durable, high strength, high pressure bearing, which can be used for a long time. 【Better Use】: The higher the speed of the drill press, the better the effect of the drill, when installing these diamond glass jewellery drill bit tipped for drilling, the speed of the drill needs to reach 2000 RPM, please use cold water when drilling. 【Dimensions】: Length: Approx. 36mm/1.41", Shank Diameter: 0.6mm/0.02", Head Diameter: 1mm/0.04", these diamond coated lapidary drill bits are lightweight, compact and easy to handle. 【Widely Used】: Our solid bit needle with high precision, more accurate grinding, suitable for jewelry, ceramics, jade, agate, glass and semiconductor materials, etc., which is a good drilling tool for you to choose from. 【Kindly Reminder】: If you use the twist drill bit for many times, it will not be very sharp than the first time using. You could cut a little the top of it with plier, it will become sharp again.