I am trying to understand more about my cameo ring

by Angele
(Seattle)

With the help of my friend I was able to capture close ups of the markings.
Is this a roman goddess piece? Who is she? What does S.N. mean? Is it coral (I tried the hot stick pin method on the back of the cameo so I believe I can rule out resin)?

It is just driving me crazy NOT knowing about and apparantly not looking in the right places to get the history. So Thank you for any information you can provide to me! It will be better than my normal response "I don't know but I think it's real pretty.."