Cut glass has a sharp and irregular edge, which is eliminated through a grinding process (manually performed or through CNC machinery) that removes and uniforms the edge of the glass in many different ways, according to the desired processing. Round lucid membrane: the edge looks rounded and lucid, high ranking of processing. Flat lucid membrane: the edge looks lucid and perpendicular to the surface but the junction is bevelled at 45°; high-ranking processing. Raw membrane: same of lucid membrane, it little differs because the edge doesn't look lucid but opaque and has a bigger roughness. Bevelling: glass edges are grinded 10-40 mm in height to create a 7° angle relative to the surface of the glass. The edge grinding is occasionally made for costs purposes in particular on colored glasses in order to limit the thermal shock fenomenon although for this fenomenon the distemper of the sheet is advised.