Descriptions:Our lapidary drill bits are made from diamond powder, precise and sturdy. It is perfect for drilling holes on the jewelry, ceramic, jade, agate, glass and amber etc. Using high-speed of drilling machine to drill will lead to a good drilling effect. Please use cold water to drill. Our drill bits are very sharp and you could use them for many times. It is a good drilling tool for you to choose from.Features:Made from diamond powder, high-quality, precise and durable to use.Idea for drill holes on the jewelry, ceramic, jade, agate, glass, amber and semiconductor materials etc.The higher speed of drilling machine, the better effect of drilling bits.The speed of drilling machine need to be reached 20000 RPM when you use our drill bits to drill holes.If you use the 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.Please Kindly Pay Attention:-Use cold water during the drilling hole operation-Use high-speed(Up 20000 RPM) to drill holes with our drill bits.-Be stable, don't shakeSpecifications:Condition: 100% Brand New and High QualityMaterial: Diamond PowderColor: SilverLength: Approx. 36mmDiameter of Shank: 0.6mmDiameter of Head: 1mmWeight: Approx. 4gQuantity: 20PCSPackage Included:20 x Lapidary Drill BitsPlease Note:1. Please allow some errors due to manual measurement 2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard..