Need to add a cable access point to a granite kitchen worktop. I had my doubts, but I followed a pro's instructions and this workshop cut through a full inch of hard granite. Just used a Makita 18V drill bit and made a damn hole with ice water and used turkey lube to constantly remove dirt and add fresh ice water. The bigger the hole and the harder the material, the slower you need it, so I set my Makita to the 0-400 RPM setting. Also uses a Milwaukee mandrel with a retractable hole saw starter attachment. finish pushing to the end. Make sure you put a bucket under the hole so the core falls into the bucket once you break through the water. I spent time wetting, cleaning and re-wetting the area but I would only estimate the total drilling time to be around 5-10 minutes. I also rocked the bit back and forth a bit from time to time. This product did the job and did it well.