Nanodiamonds containing nitrogen-vacancy (NV) centers can be prepared using irradiation with high energy electrons. Nanodiamonds with low numbers of NV centers (ideally, single defect centers) are suitable for quantum signaling, optics, and computing applications because their fluorescence allows for observation of single quantum systems. These particles have approximately 1-4 NV centers per particle as measured using AFM confocal microscopy with subsequent derivation of the correlation function using a Hanbury-Brown-Twiss setup.