Where can i find out if my gold and diamond jewelery is real?

I have a box of old jewelery/ but i don't know whats real and what fake. Im in need of money so i dont want to get ripped off. i want to take it someplace were they can tell me whats real, and then take it somewhere else to sell it. any ideas? i live in the st.louis mo area. also some of the jewelery is damaged so i need to find a place to sell damaged jewelery too.