The chemical characteristics of natural and synthetic emeralds were studied in order to identify differences that could be used to separate them from one another. 38 natural emeralds from 20 localities and 11 synthetic stones from six manufacturers (flux and hydrothermal growth processes) were analyzed by microprobe and x-ray fluorescence. The results revealed a complex collection of chemical constituents that reflect the different environments in which natural and synthetic emeralds form. The present study agrees with the limited number of analyses previously reported for both materials. Thus, a new method of distinguishing natural from synthetic emeralds is now available for use in gemology when more conventional methods prove inadequate. -- AATA