Info on a pendant I inherited with initials FC on back

by Andrea T Sierra
(San Antonio, TX)

I inherited a pendant from my great grandmother (she resided in Oaklahoma in case that helps) along with a choker. I know the choker is real silver, but it has no numbers or markings of any kind. My interest, however, is in the pendant. I am sending pictures; as you can see, it is a single, large piece of turquoise n a silver setting with the initials FC on the back. The pendant alone weighs 12.23 grams. I believe that I have dated it to 1940, but can not be sure. Any information you have will be utterly appreciated. Email is the best way to contact me.

Gratefully,
Andrea Sierra