Lighter hammers weighing one pound or less are best for doing lettering work. Every hammer has its own feel, so choose one with a grip and heft that you're comfortable with. Pneumatic hammers are powered by compressed air and house chisel bits within a cylindrical housing, delivering more strokes per minute than muscle alone is capable of. The 1/2 inch diameter pneumatic hammers are best suited for lettering, as a larger pneumatic hammer's power is likely to bruise the stone, leaving behind a white mark that will be visible after you polish the finished lettering.
Hardened steel chisels are best for carving softer materials like soapstone, while carbide- or diamond-tipped chisels have the strength you'll need for working with granite. Point chisels are appropriate for roughing out your design and then use a narrow flat chisel for the finer details of your lettering. You'll need tooth chisels to level any bumps and depressions left after working with your point chisels. Finish refining your lettering with flat and rondel chisels, which smooth over rough and jagged areas tooth chisels leave behind.
Die grinders are hand held rotary tools that can accept interchangeable bits and burrs you can use for detail work. Grinders have a standard 1/4 inch shank size, but you can buy attachable collets, adapters that allow the grinders to take attachments with 1/8 inch shanks. Carbide- or diamond- tipped burrs are good to have on hand if you're working with hard stone such as granite and you can also equip your die grinder with sanding and polishing attachments for doing finishing work.
A sandblaster uses compressed air to turn abrasive particles into a carving tool. The sculptor creates a rubber stencil with the lettering and design he wants etched into the stone and fastens it into place. The sandblaster's air compressor fires the particles through the hose and nozzle at a pressure of 40 to 100 pounds per square inch (psi) and carves the image into the stone. Sandblasting produces particulate debris which can cause respiratory disorders, so goggles and a respirator are essential to any sandblasting work.