- The application of focused ion beam milling method to produce high aspect ratio, sharp spherical diamond indenters for nanoindentation measurements was discussed. The method was used to obtain a spherical well-defined super tip at the apex of the indenter, with a radius of 53.4 nm. The indenter was used used in sub-10 nm nanoindentation measurements on fused quartz and silicon. It was observed that the tip showed long-term resistance against plastic deformation and wear. The transition from elastic to plastic contact occurred at shallow contact depths was due to the small size of indenter tip.