In order to look for differences in visible light disperison by glass particles, refractive index measurements were made at various wavelengths. It was established that the most practical wavelengths for obtaining characteristic data were in the blue, yellow and red regions. A collection of glasses was then examined to establish whether or not discrimination between them was improved by measuring dispersion. It was shown that, for glasses of the type commonly encountered in casework in the UK, dispersion measurements are unlikely to enhance the evidential value.