Old pearl ring

Went to an estate sale over the weekend. The woman who died had a huge assortment of vintage costume jewelry and some real. One of the treasures I walked away with was this huge pearl ring. Victorian style could see some classy lass from the 20's wearing this piece. The pearl when I got it was loose, the part where it's glued had a twisted silver like screw - not pointed. I had a local jeweler reglue it for me. It's set in sterling- marked 'Ster'. Not sure of actual age. I looked at the pearl with my 10X loop and shown very fine grained poors. Which I believes means it's a real pearl then again could be coated not too sure. Any helpful info much appreciated!