An observation and analysis method for observing and analyzing optical singularities that deflect light and that are carried at the surface or in the wall of a container made of glass and possessing an axis of symmetry, the method consisting in: • illuminating the container by means of a diffuse light source presenting variation in a property of light along a variation direction; • placing at least one image acquisition device sensitive to said property of light and to its variation so as to take at least one view of a container portion that might contain optical singularities when observed from at least one viewpoint along an observation axis; and • processing at least one view in order to analyze the optical singularities; the method being characterized in that it consists in: • illuminating the outside of the container by using a light-emitting surface of axial symmetry around a vertical axis parallel to the axis of symmetry of the containers, with the variation direction of the light property running along a generator line of the light-emitting surface at all points of the light-emitting surface; • with containers of low transmittance, taking the view of the container portion by the image acquisition device receiving light beams coming from a portion of the light-emitting surface of axial symmetry situated on the same side of the container as the viewpoint, which beams are reflected by the surface of the container in application of the laws of specular reflection; • and with containers of high transmittance, taking the view of the container portion by the image acquisition device receiving light beams coming from a portion of the light-emitting surface of axial symmetry that is diametrically opposite from the viewpoint relative to the container, which beams have been transmitted through the walls of the container in application of the laws of refraction. • illuminating the container by means of a diffuse light source presenting variation in a property of light along a variation direction; • placing at least one image acquisition device sensitive to said property of light and to its variation so as to take at least one view of a container portion that might contain optical singularities when observed from at least one viewpoint along an observation axis; and • processing at least one view in order to analyze the optical singularities; • illuminating the outside of the container by using a light-emitting surface of axial symmetry around a vertical axis parallel to the axis of symmetry of the containers, with the variation direction of the light property running along a generator line of the light-emitting surface at all points of the light-emitting surface; • with containers of low transmittance, taking the view of the container portion by the image acquisition device receiving light beams coming from a portion of the light-emitting surface of axial symmetry situated on the same side of the container as the viewpoint, which beams are reflected by the surface of the container in application of the laws of specular reflection; • and with containers of high transmittance, taking the view of the container portion by the image acquisition device receiving light beams coming from a portion of the light-emitting surface of axial symmetry that is diametrically opposite from the viewpoint relative to the container, which beams have been transmitted through the walls of the container in application of the laws of refraction.