Samples of BK7 and SF10 optical glass were 'ductile' ground using a cast-iron diamond ring tool with an electrolytic in-process dressing system. Selected machining parameters gave nanometric quality surfaces (Ra < 2 nm) with minimal sub-surface damage. Relatively rough brittle fractured surfaces were obtained by machining the glasses with the same diamond wheel but without the assistance of electrolytic dressing. The grinding force (normal) generated whilst ductile machining was significantly greater than for brittle fracture grinding. The work described in this paper reveals a significant advance in the machining of optical glass. This novel and complex process requires further investigation to provide a full understanding of the science involved.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.