Heart Shaped February Birthstone Ring Sterling Silver Sz 5

Dainty ring with faceted heart shaped purple stone. Not sure if it's amethyst, tanzanite or another semi precious crystal. 5 prong setting. Vintage ring stamped STER with a cursive L inside a heart. Have not yet identified the maker so if you recognize it please share. Very pretty small ring size 5. Please review the photos and comment for more information.