These garnet cabochon diamond earrings were made in the late 19th century, somewhere around 1870. At that time cabochon garnets were the thing to wear. It was a throwback to the Renaissance. Elements of the highly decorative Renaissance jewellery were being used and simultaneously people rediscovered the roots of European high culture, the Etruscans, the Greeks and the Romans. This had everything to do with the archeological excavations of the ancient sites and the finds they discovered under the earth. 
Elements and combinations of techniques, like the cabochon carved stones in this case, were re-used in jewellery making. In this case the spade-like leafs on top of the garnets, decorated with tiny rose-cut diamonds, and the golden mounts at the back, tell us that the earrings were made in the 19th century.