Several techniques have been proposed for the production of NDs, including nanomilling of bulk diamond, detonation diamond and high-power laser ablation . Detonation NDs tend to be small (5-10 nm) and rich in impurities . High-power laser ablation can produce fluorescent NDs in a single-step process , but the yield is insufficient for practical application. Conversely, nanomilling of bulk diamond makes it possible to control concentration of defects and NV centers, as well as particle size, with good production yield .