A method and apparatus for remotely verifying the calibration status of a diagnostic instrument, for example, following remote installation of a software upgrade on the instrument. In one example, a method of verifying the calibration status of the instrument, includes retrieving stored raw calibration test data generated during a previously-performed calibration of the instrument, processing the raw calibration test data to generate a diagnostic reading, comparing the diagnostic reading to a known nominal reading, and based on the comparison, generating an output indicative of the calibration status of the instrument. In one example, the method is performed without contemporaneously measuring a calibration object with the instrument and therefore, without activating the measurement head or measurement optics of the instrument.