Circular saw blades differ in diameter, the material they're made of, how many teeth they have and how big the teeth are. Different combinations make each blade ideal for a certain type of job. For example, some circular saw blades have diamond-tipped teeth so they can easily slice through hard materials such as ceramic and glass. Laminates are essentially layers of paper tightly pressed together and glued with a resin. To cut through laminate countertops, you can use a hand saw, but a circular saw makes the job much quicker.
Because a circular saw can produce jagged edges and chip the laminate, your best bet is to lay the laminate face-side down and cut from the back to the front. Mark off the line you want to cut using masking tape, and make sure to leave a bit of extra room for overhang, which you can later cut off. The best circular saw blade for cutting through laminate for a kitchen counter is one with many fine teeth -- at least 40. Blades with carbide tips tend to last longer than regular steel. In addition, you should choose a narrow blade, or one with thin kerf, as it's called in saw talk.
To protect the finish on the laminate, you may want to duct tape the saw's shoe so that it doesn't scratch up the surface as you move along with the saw. Of course, if you're cutting through the back to prevent tear off, you probably won't have a problem with the finish. In terms of safety, you need to keep an eye out for kickback potential. If your circular saw blade gets pinched in the laminate, it will pop out and fly quickly toward you. To minimize the risk of kickback, double check that the blade is clean and sharp before you begin cutting, and always wear safety glasses and other protective equipment.