Vintage Avon Silver Ring with Iridescent Mother-of-Pearl Oval

Avon ring showcasing an oval iridescent mother-of-pearl stone. Polished silver-tone setting frames the pearly centerpiece. Subtle multi-hue shimmer adds luminous interest. Sleek band for everyday wear. There’s a mother of pearl it is vintage. It’s a size 7 1/2. I’m unsure about the marking on the inside. I know I’ve owned it for over 10 years and washed it many times and jewelry cleaner has never tarnished nor broke me out. I do have a metal sensitivity so I do believe it’s Sterling silver don’t quote me though. I’m not a jeweler.