These earrings are set with Rosarita, a slag glass produced in the smelting of gold from beach sand in Alaska, a process that has not occurred since the 1970s. Beach sand was dredged from beaches in Alaska, and the sand smelted on shore, leaving this glass. Nome, Alaska, located on the Norton Sound of the Bering Sea, was one of the places rosarita was produced. These earrings are etched on the backplate of the stone with a section of topographic map from Nome, echoing it's origins (image courtesy of the USGS).
The etching process includes the photo or drawing being transferred via laser jet printer to PCB circuit board thermal transfer paper. The image is then transferred to the metal at 150 degrees C via a hot plate; the jet printer ink functions as a resist leaving those areas un-etched. The etching is done in a bath of ferric nitrate.