A diamond drill is a very powerful tool that you can use to make holes in stone , brick , block , concrete and reinforced concrete and similar material. They have different usages like cutting holes through walls for plumbing pipework or cutting holes for stair railing and alike. You can use an extension for drilling long holes and it extends the reach of the drill. You can use diamond drills with or without water but it is good to know that water extends the life of diamond drill bits dramatically. When using water with don't use too much water. If you want to get the better result you should apply water until the slurry look like cream. If slurry Is proper , it keeps the bit cool and it helps the process of grinding.