Antique Brooch/Pin

This item was found in our familys estate. It belonged to my grandmother. It has been in the family for over 90 yrs. It was passed down to me from my mother, from her mother. It must have had some speciality to it for her to have passed it down. My grandfather was a very wealthy man, so I'm sure he paid a pretty penny for this. (what would seem like a pretty penny back in the day anyway) My grandmother would wear this Brooch/Pin out on special occasions. My mother told me that she would have her "Go Get My Special Pin" for her to wear. Anyway, I am 53 now, so I know this piece is Very old, and I need some help with it.