Vintage Sterling Silver Black Agate Cameo Ring

Item is in good used vintage condition Medium to heavy wear & scratches No makers marks Item acid tested positive for sterling silver I’m am not sure what the back stone is possible glass? It is chipped in multiple places. it’s hard to see. see last 3 pictures for examples. it’s like this all the way around the stone/glass Please zoom in & see all pictures The black cameo could be black agate or onyx..not sure Size is approximately 11 1/4 to 11 1/2.. Appears to have been handmade…