How to Cut Granite
To safely cut granite, lay a piece of masking tape over the line you plan to cut, then draw a straight line over the tape with a marker. Fit your circular saw with a diamond-cut blade, then turn on the saw and carefully begin cutting into the granite. To keep the saw from overheating, either have someone else spray the granite with water, or use a wet saw, which will spray water as it cuts. Remember to wear safety goggles and a dust mask when you're working with the saw, but do not wear gloves, as they'll weaken your grip on the saw.
Wear safety goggles and a dust mask while handling the saw. This will keep granite dust from harming or irritating your eyes while you cut. If you're working in a dusty area, put on a dust mask as well to keep your lungs clear. You may also want to wear earplugs or protectors if you are sensitive to loud noises. Do not wear gloves while using a saw. No gloves are strong enough to protect your fingers, and gloves will weaken your grip on the saw. Keep your hands bare and free of any bracelets and other jewelry to avoid snagging your hands on the blade. Tie back any loose hair and avoid wearing baggy clothing. Take off all accessories, especially face and hand jewelry, before you use the saw. Roll up your sleeves so your forearms are bare to keep any fabrics from getting caught in the saw. Check the saw for the correct blade before cutting the granite. Make sure you have fitted your saw with a diamond-cut blade in the right size. The wrong size or type of blade can damage your saw and potentially result in injury. Use a tape measure or straightedge to plan your cut. Between the options, a straightedge is preferred because it can keep your line more even when you're ready to mark it. Position the tape measure or straightedge slightly to the left of the line you want so you can mark the line with tape later. If you're cutting something that's square or rectangular, make sure the tape measure or straightedge makes a 90-degree angle with the side of the granite so your cut is precise. Place a line of tape directly to the right of the tape measure or straightedge. Painter's tape or masking tape is ideal because it is easier to readjust. Apply it as close to the measuring tool as possible to keep your line straight and even. Draw a straight line over the tape with a marker. This is the line your saw will follow as you make your cut. Use the measuring tool to keep the marker line straight as you draw it over the tape. If you mess up on the line, remove the tape, reapply a new strip, and start over. Avoid drawing directly on the granite. If you make a mistake on the line, it will be harder to remove. Use a diamond-cut blade to cut the granite. Granite is one of the most difficult rocks to cut because it is so hard. Most saw blades will not be equipped to cut granite without damaging them. Fit your saw with a diamond-cut blade for the sake of precision and safety. Position your circular saw over the granite. Before you turn on the saw, it should not touch the granite. It should, however, hover directly overhead. Line up your saw blade as closely with your marked line as you can so your cut starts and ends even. Turn on your saw and begin cutting the granite. Carefully move your blade into the granite without using heavy pressure. Guide it along the line as evenly as possible for an accurate cut. Stand to the side of the saw instead of directly behind to protect yourself from kickback. Spray the granite lightly with water. Have a partner spray the granite with a spray bottle as you cut through the line. This will keep the saw blade from overheating from pressure. If you don't have a partner, rent a wet saw. Wet saws spray water over the rock and blade as you cut. Always use both hands while operating the saw. This will give you maximum control over it to prevent slipping or kickback. Although you can use a circular saw with one hand, you will not be able to make a safe or accurate cut. Stay concentrated on the blade as you cut through the granite. Never look away from the saw while it's still on. A moment's distraction can result in damage to your project or even serious injury. Avoid forcing your saw through the rock too quickly, as going too fast can cause kickback, which may injure you or damage the granite. Inspect your finished cut. If it looks satisfactory, begin prepping your next cut or wrapping up your project. If you notice any uneven lines or are otherwise unsatisfied with your cut, however, mark the areas you want to fix and re-cut the granite. Use a dry cut diamond angle grinder to make smaller cuts. An angle grinder is better than a saw at trimming granite or making cuts that do not go through the entire slab. Choose an angle grinder equipped with a dry cut diamond wheel, which is strong enough to cut through stone. Hold the granite slab on a flat surface while using the angle grinder. Clamp the granite slab firmly to a flat surface (like a workbench) and move the angle grinder gently across the granite where you want to make your cut. Apply light pressure to the granite, and stop every 10-20 seconds to prevent going too quickly or putting too much weight on the granite. Drill holes in granite using a 1⁄8 inch (0.32 cm) to 1.25 inches (3.2 cm) drill bit. Depending on your needs, these sizes offer enough range to drill into the granite without damaging it. Mark your measurements with painter's tape before you begin drilling so your holes stay even and precise. Drill straight down into the granite. If you angle the drill, you risk chipping or cracking the granite while drilling. Apply even pressure to the drill as you work downward, and drill slowly so the drill does not slip from its mark. 
Wear safety goggles and a dust mask while handling the saw. Do not wear gloves while using a saw. Tie back any loose hair and avoid wearing baggy clothing. Check the saw for the correct blade before cutting the granite. Use a tape measure or straightedge to plan your cut. Place a line of tape directly to the right of the tape measure or straightedge. Draw a straight line over the tape with a marker. Use a diamond-cut blade to cut the granite. Position your circular saw over the granite. Turn on your saw and begin cutting the granite. Spray the granite lightly with water. Always use both hands while operating the saw. Stay concentrated on the blade as you cut through the granite. Inspect your finished cut. Use a dry cut diamond angle grinder to make smaller cuts. Hold the granite slab on a flat surface while using the angle grinder. Drill holes in granite using a 1⁄8 inch (0.32 cm) to 1.25 inches (3.2 cm) drill bit. Drill straight down into the granite. 