Virgin Mary Shell Cameo

I just recently purchased this cameo to wear for Christmas and Easter and enjoyed wearing her over this past Christmas season. The pin has been removed and there are no markings. The setting is some type of gold vermeil over what looks like copper, and there is a lot of finish that has faded away. There is a hook on the back that I added a temporary jump ring when I wore it so I could slide a chain into it, there is no bail. I would love to have the cameo re-mounted into a better setting one day, hopefully from a similar size antique cameo, but I am also concerned about removing the original setting. It was difficult finding a gold chain that looks good with the setting due to the color of the finish, I had to use an old costume chain, going to try a sterling silver chain next, since there is spring wire edging. I would like to know if anyone can confirm the age, and any other information is appreciated. Thanks so much!