In this paper the deterioration processes of glass are described with particular reference to beads on ethnographic objects. With beaded objects the most obvious symptoms of glass deterioration are cracked and broken beads. The more subtle symptoms include: crusty deposits on beads or threading material, a fine network of cracks, known as crizzling, present over the entire surface of beads and only detected under a microscope, a sticky or sweaty surface on the glass and internal cracking. Symptoms which appear on the substrate and are much less common include: bleached images of the beads on wool or silk substrates directly below the deteriorated beads, and substantial darkening of the skin or leather directly in contact with the beads. The emphasis of the paper is upon identifying the subtle early symptoms of glass deterioration so that preventive conservation techniques outlined in the text may be implemented, thus retarding the deterioration process.