Native American Navajo Sterling Silver Dragons Breath Art Glass Earrings

Dating to the 1960s/1970s or so, may I offer this pair of screwback earrings designed in a Native American style. Made for the Trading Posts during the heyday of the Indian Jewelry carze, the fronts of the earrings are marked STERLING while the back mechanisms seem to me to be made of Alpaca or some sort of silver amalgam. It's possibly they too are Sterling but my gut tells me otherwise. The earrings also have the pleasure of still bearing the original black grease pencil design mark - that, in itself, is a hard this to find. The fronts of each hold a stunning Dragons Breath Art Glass oval cab. Height is 3/4" of the entire piece x 1/2" wide. Combined weight of the pair is 7.9 grams. Condition is very nice with a mellow patina to the metal. A light polish to the front should bring up a bit more sparkle. Lovely pieces with the back mechanisms working as they should. Leave as is or repurpose into another design.