A method of determining a presence of a wire-edge at the site of an internal edge of a ring surface of a ring of a container includes lighting of the ring surface of the container from above using a radial light beam at 360 and observing the ring surface according to a peripheral observation field. A first principal circle is formed in a first image zone. At least one secondary arc of a circle concentric to the first so-called principal circle, and radially offset relative to the latter is also formed in the first image zone. The first so-called principal circle and any first secondary arc of a circle are searched using the first image zone. A device for executing the determining method is provided along with a line including the device.