Efforts to optimize precision machining emphasize form and surface finish as the primary objectives. Minimizing subsurface damage is no less important for high power optics. This paper reports our usage of instrumented microindentation for subsurface damage assessments. Our instrument is an example of a new class of diagnostic tool. All apply controllable loadings to an indenter and continuously measure the load and resulting penetration. The utility of microindentation depends on appropriate interpretations of load-depth curves. The technique provides insight into the physical nature of the subsurface and is a means to obtain a variety of engineering properties from the subsurface region. We use it to profile flow stress and elastic modulus with depth, and to gauge creep and anelastic behaviors. Instrumented microindentation promises rapid and sensitive property assessments. We will use a range of examples to show this potential is realizable.