Assess the ends of the beams where they meet the wall. Depending on the type of ceiling, there will be a large or small gap between the ends of the beams and the wall.
Apply caulk or putty to minute spaces between the coffered ceiling beams and the walls. These tiny gaps are the result of imperfectly cut beams or casing, but are easy to fix to make a seamless end to the coffered ceiling.
Install crown molding around the top of the ceiling, against the wall and beams, for coffered ceilings where a larger gap has been left. This can be an extremely attractive solution for creating an end to a coffered ceiling, adding to the architectural drama of the room.
Install a carefully placed final beam for coffered ceilings that are installed on a grid in a room that lacks a definitive end -- for example, a dining room that shares a ceiling with an adjacent kitchen, and lacks defining separating architecture, such as a doorway. When coffered ceilings are constructed on a grid, crisscrossing the ceiling, one of the beams and its casing will serve as the end of the coffered ceiling, creating a visual end to the room as well.