How many pieces you will get out of cutting some rock with a blade that was not intended for cutting rock is subjective. You might get one you might get 100. Its kind of hard to answer that because rocks also have different compositions. More than likely the blade will be trashed, so just decide to go for it or buy a more suitable blade. If I remember right, the saws that are marketed for fragging corals are diamond type cutting blades. Also you need to take a look at the blade and make sure to try and get most of the oil off of the blade. Many times companies put a light oil based film on their cutting products to keep them from rusting. Unless they are painted. But my last drill index i bought had a light film of oil material on all of the drill bits. So just be mindful of that before you start cutting. If you have that oil on the blade and you start cutting, you may transfer some of the oils into the rock. Im not saying that every cutting blade has this, many sawza blades are painted instead, just check it out to make sure the oil slick is not on the blade before you cut.