Here is a pair of vintage Native American ~ probably Navajo ~ turquoise and sterling silver earrings. The screw-backs look newer than the earrings and the screwback heads do not match one another. They may have been added later.
Each earring measures 3/4 inch long not counting the screwbacks. Each earring weighs 4.5 grams. One earring has a mark on the back, as shown. Not sure if this is a hallmark or not.Screw-backs. Circa 1970-80s
As is the case more often that not with the earlier Native American jewelry, these earrings is not marked for silver content or maker. However, I guarantee that they are coin silver (.900/90%) or sterling silver (.925/92.5%). When I test jewelry for silver content, I never drop the testing solution directly on the piece of jewelry since the acid could damage the piece. Rather I rub the piece against a testing stone and drop the acid on the testing stone.