The surface orientation and detailed defect microstructure of polycrys
talline diamond can be observed in a scanning electron microscope thro
ugh local changes in the surface conductivity. The electron contrast i
n uncoated samples is straightforward to distinguish when the rms surf
ace roughness is less than about 2 nm. This degree of smoothness occur
s on some of the faceted surfaces of individual diamond grains but can
also be achieved by polishing. The contrast, observable only in the s
econdary electron imaging mode, shows a strong dependence on both beam
voltage and current. It is postulated that the contrast is produced s
olely by the differential rate at which the electron beam-induced char
ge can be locally dissipated through crystalline defects and grain bou
ndaries in the otherwise highly nonconductive diamond matrix. The appe
arance of the charge-related contrast requires that highly connected p
athways exist between the crystalline defects and the high-angle grain
boundaries.