The paper describes a technique for the synthesis of microdiamonds, germanium nanoballs and nanotubes in an argon-germanium arc. The evaporation of germanium atoms was carried out from the surface of a graphite rod, which served as the anode of the arc discharge. The synthesis of microdiamonds was observed on graphite substrates near the anode; germanium nanotubes and germanium nanoballs were also found nearby. It has been established that germanium promotes the synthesis of nano and microdiamonds. Synthesized diamonds have a classic structure with rectangle faces and four hexagons adjacent to the edges of this rectangle. The sizes of microdiamonds reach tens of microns. The diameters of germanium nanotubes are of the order of 50-100 nm, and the length is of the order of 10 μm.