Impact damage is one of the commonest form of ‘spontaneous’ breakage of toughened glass, often from deliberate impact, such as throwing stones, pellet guns etc. It can be very difficult to identify because the ‘star’ pattern seen in annealed glass is overwhelmed by the innate fracture pattern of the toughened glass which often falls from the frame. The impacting object, a pebble or air gun pellet may not end up in the vicinity of the broken glass which can then lead to the misconception of ‘spontaneous fracture’ being deemed as the cause of breakage.