Nicolock PA- VER OUT COR MB Marble Blend Versailles Outside Coping. The coping is the top layer of thin, flat stones commonly found on a retaining or garden wall. The coping acts as the cap, or the topmost layer of stone on a stone wall or the decorative edge around a pool. While it does provide a decorative finish, coping can also help assist in water runoff when installed at a slight angle.