The are many different edge details available for granite countertops. The choices will depend on the equipment your countertop fabricator owns, the skill of the fabricator and the price you are willing to pay.
Some of the most common are shown in this picture.
You can add drama and cost by increasing the thickness of the appearance of the edge. This is done by laminating an additional piece of granite to the edge of the slab then molding the edge like the edges on the right in the picture below.