The present invention provides a scalable method for achieving shape control of diamond micro-nanoparticles, comprising air oxidizing diamond micro-nanoparticles grown by chemical vapor deposition and/or diamond micro-nanoparticles grown by high pressure and high temperature. The present invention achieves the controllable morphology transformation of diamond micro-nanoparticles via air oxidation treatment. It has been demonstrated that a series of unique shapes, including “flower” shaped, “hollow” structured, “pyramid” patterned on the surface, and “boomerang” shaped, can be achieved by altering the air oxidation parameters, i.e., temperature and duration. The scalable production of these differently shaped diamond micro-nanoparticles represents a significant scientific breakthrough together with a high commercial value. The ability to produce diamond particles with desired shapes simply and cost-effectively will remove many obstacles to using diamonds for practical applications in nanophotonics, quantum computing, quantum optics, etc.