So ornate - this is a beautiful piece. The large green stone is glass not Lucite. The pin measures 2.75" across. All the tiny stones are pave set - the large stone prong set. Surrounding the large stone there is a bit of patina that I did not attempt to polish. I will leave that to you. It's a regular bar pin with a secure clasp. This one's amazing.
I'm putting is at 1940 but again I am no expert. Based on the information told to me buy the seller this item belonged to her mother. She thought it was Victorian. I'm thinking not so - please see the backside of the pin in the last picture. I find that "V" mechanism n 1920 - 1940 items. I love this piece - almost kept it.
Will ship via USPO with delivery confirmation.