Review on DAMO Diamond Concrete Granite Marble Cutting Tools: Efficient Industrial Drill Bits by Jeff Payne

It worked like clockwork. I and a friend made three holes in a 3/4 inch granite countertop and misted the area with a water sprayer. I also put masking tape on the area to be drilled and marked the circle (using the same 1 3/8 bit). Pencil. Here's what YOU NEED TO KNOW: Start drilling the hole at about a 45 degree angle. The drill hits the granite directly without rolling. (Duct tape can also help). Slowly move the drill up and down vertically while continuing to drill. I made three holes this way with no problems. You can also go to YouTube and watch how "drilling holes in granite" is done. I used a fairly powerful electric drill (had to buy an adapter). It took about 2 minutes for each hole. I applied pressure but not much, I let the drill do most of the work. If you use a grinder instead, it might go a little faster. PS I made these holes in my office table top to make it easier for me to route all the cables (computer, printer, phone, etc.). If you do a similar "office" job, check out Amico's (Revain) 1.3" Computer Desk Cases, which fit perfectly into 1 3/8" openings for a totally professional look.