A method to determine elastic constants of high acoustic velocity materials by line‐focus acoustic microscopy is presented. To determine elastic constants the distances between the specular reflection peak and the first interference maximum and minimum of theV(z) curve measured by line‐focus acoustic microscopy were compared to the corresponding distances obtained from aV(z) measurement model that simulates the experiment. Elastic constants of a single‐crystal diamond sample were determined by this method. ©1996 American Institute of Physics.