Review on DAMO Diamond Cutting Tools for Concrete, Granite, and Marble by Brant Skogen

Used to install a new drinking water faucet. Passed and an inch-thick granite countertop, like butter. Make sure you start the hole at an angle and keep the drill bit cool by dipping it in water from time to time. When I say start the hole at an angle, I mean hold the drill at a 45 degree angle to the countertop and run the drill at high speed before touching the surface. Then lower the drill bit onto the table top at a 45 degree angle until it touches the surface. Be ready to secure the drill so it doesn't jump over the counter. Starting the drill at an angle greatly reduces the chance of it slipping. If you grind the chisel a little at an angle, you can start rotating it slowly up to 90 degrees as you drill. Work slowly and you will eventually have a good channel to stay in when you start drilling into the countertop. Much luck!