Proton induced x-ray emission (PIXE) has been used to quantify trace element concentrations in 133 natural rubies and 27 synthetic ones from 14 different sources. The results suggest that it is usually possible to distinguish between natural and synthetic stones by the higher trace element concentrations in the natural variety. Iron and vanadium are particularly good indicators in this regard while chromium concentrations can differentiate sources as a result of relatively low variations in its concentration within a given source either natural or synthetic. For natural rubies a listing of the visually identifiable inclusion minerals is given for those sources represented in the study. These observations are perhaps the most broadly applicable results to smaller institutions.