Defects on diamond surface have a profound effect on certain properties of the diamond, enabling these properties to be tailored to the specific needs of important applications. A simple and practical method is described to repair the diamond particles with surface defects. The low grade diamond particles were repaired by hotfilament chemical vapor deposition with low carbon concentration in feed gases, and the defects on the surfaces disappeared because of the simple film formation and homoepitaxial growth mechanism during the CVD process. This efficient and simple method provides a way to extend its useful life during the actual application. (C) 2014 Elsevier B.V. All rights reserved.