The result of a failure analysis, a glass expert presents several views of a 180µ diameter origin (nickel sulfide particle) of a failed tempered glass door. The upper left photomicrograph is taken with a low power optical microscope and it includes the NiS particle and the initial Wallner lines. Upper right and lower left are taken with a high power optical microscope. with and without Nomarski. Finally lower right is an Scanning electron microscope photomicrograph of the same particle. The inportance here is that the distinct shape and surface of a NiS particle makes it identifiable with an optical microscope.