Possible Family Heirloom - necklace 750

by Shell
(NJ)

I have a necklace with a religious pendant attached that belonged to my Great Grandmother who died in the late 1930s. She came here from Italy. The chain itself looks to be gold but is marked with the number 750. There are three markings on the back of the pendant. One says 750 but I cannot make out what the other two say with a magnify glass. I guess I want to know if there is a way to date this to see if it really was my Great Grandmother's and if it came from Italy without having to pay a jeweler for an appraisal.