Measure the space where you plan for the stone to fit. Generally, you want to use the natural edges of the stone toward the center of the pattern with the edge to be trimmed on the outside of the design or walkway.
Mark the stone where the cut is to be made with a pencil. Make sure you score a good heavy line so you can see it when cutting dust starts to fly.
Place the stone on a stable platform for cutting. You don't want a wobble in your work surface once you've started cutting. Waist high is best with plenty of area to work.
Make a shallow score cut with a grinder. Start on the edges of the stone and work toward the top. This will create a lot of dust, so don't hesitate to stop if you feel the need. Remember not to add water to keep the dust down. A standard grinder is not recommended for wet use.
Make a full depth cut following the shallow score. Depending on the thickness of the material, make a full depth cut from one end to the other.
Remove excess dust from the stone with a medium-bristle brush. Make sure the stone is as clean as possible before setting it in the final position.