Vintage Large Silver Filigree Engraved Puffy Heart Pendant On Chain

Excellent vintage condition, but no clasp on chain anymore. Could be worn on a new chain of course. Really pretty large ornate engraved filigree design puffy heart. I found some listings saying this was sterling silver, but there are no markings and I haven't tested it, so I can't be sure. To me, it does have the look, judging by the correct aged patina, but that could also mean its silver plated. It is definitely old, as it belonged to my great aunt who passed many years ago. Some listings said this was an Art Nouveau piece. There were other listings that looked like they were replicas of this piece, but you can tell the difference in quality which makes me think this could very well be one of the original sterling silver, or at least silver plated, pendants. See pics for measurement. Thanks for looking, and feel free to ask questions or make an offer!