From BiblePortal Wikipedia

Smith's Bible Dictionary [1]

Amulets. Amulets were ornaments, gems, scrolls. Etc.. Worn as preservatives against the power of enchantments, and generally inscribed with mystic forms or characters. The "earrings" in  Genesis 35:4 were obviously connected with idolatrous worship and were probably amulets taken from the bodies of the slain Shechemites.

They are subsequently mentioned among the spoils of Midian.  Judges 8:24. In  Hosea 2:13, is another like reference. The "earrings" in  Isaiah 3:20 were also amulets.

Holman Bible Dictionary [2]

 Isaiah 3:20