MicroRaman spectroscopy has been used to measure stress in diamond with improved precision. Stress was induced by rf sputter deposited tungsten films of 1- and 9-mum thickness. Preliminary data showed a systematic error in the diamond Raman peak position of about 0.05 cm-1/scan, which led to inaccurate and imprecise stress measurement. A new technique, using a reference 5520-angstrom krypton line only 10.5 cm-1 from the Raman diamond line, results in an order of magnitude increase in measurement precision. Using this calibration, diamond peak position could be measured with a precision of +/-0.03 cm-1 which corresponds to +/-11 MPa of stress. This is an easy and inexpensive means to improve stress measurements in diamond by microRaman spectroscopy.