Cracks terminating at free surfaces are affected by local stresses in the surface region. Under residual compression the crack front must retard compared with the crack contour in the absence of stresses. This effect can be used for an identification of residual stresses at glass surfaces. For an illustration of the procedure, Vickers indentation tests in soda-lime glass are considered. Specimens treated by ion exchange and chemically toughening showed reduced terminating angles compared with untreated glass.