Blue stone is an attractive, natural stone, slightly blue in color, that is found in New York and Pennsylvania. Blue stone is available in sheets that are anywhere from one-inch-thick to six inches thick. Blue stone can be cut with a masonry blade on a circular saw, but this can cause a great deal of dust. A better idea may be to rent a power cutter with a diamond blade and a built-in watering system for dust suppression.
Mark the line of your proposed cut on the face of your blue stone using a metal square and a white crayon.
Lay a piece of scrap lumber on the bed of the cutter so that when the blade cuts through the stone it will cut into the wood and not into the bed of the cutter. Place the blue stone on top of your piece of scrap lumber. Make certain that the water reservoir on the power cutter is filled or that the cutter is attached to a water source, depending on the cutter you've rented.
Set the blade of the cutter to cut no deeper than 1/4 to 1/2 of an inch into your blue stone. Turn on the water supply to the blade and turn on the blade. Wear a breathing mask and eye protection as well as gloves. Push the blade with moderate pressure, making your first cut.
Set your blade down another 1/4 to 1/2 inch and make a second cut. Continue in this manner, making several shallow cuts until you have cut all the way through your stone.