Local fabrication of SiV and GeV color centers in diamond (or Si and Ge- based defects in other semiconductors like SiC, Si, ...) by Focused Ion Beam irradiations. The ion source is able to deliver beams of Si, Ge and Au ion species with fluences a slow as few ions per irradiated spot (max. implantation depth: 30 nm for Si and 50 nm for Ge); a laser interferometric stage allows excellent overlay and stitching.