Lay a tile face up on a workbench. Align the edge of the tile with the edge of the workbench.
Place a metal straightedge on top of the tile 1/8-inch from the tile edge. Tighten C-clamps over the straightedge, the tile and the workbench top.
Place the cutting edge of a 1/2-inch tile chisel on the exposed edge of the tile at a 45-degree angle. Tap the opposite end of the chisel with a ball-peen hammer. Continue this process along the edge of the tile until you achieve the desired effect.
Remove the clamps and turn the tile 45 degrees. Repeat the clamping and chiseling process until you have chiseled all four edges of the tile.