In the current work results of determinations of refractive index by the immersion method using a GRIM system were presented. 93 samples of glass collected in Poland from car windshields, window panes, car headlamps and glass containers were analysed. In this work an evaluation of the obtained results by chemometric methods was also presented. These chemometric methods are used to solve the problem of comparison of traces on the basis of values of refractive index determined for them.