Diamond gold toned lapel pin or tie tac?

I have this diamond patterned gold toned lapel pin or tie tac? The dimensions with tie tac and chain is around 2" long. The diamond pattern is about 1/4" x 1/2". The tie tac where the object slides into diamond pattern hole says Hickok on one side and U.S.A. on the other side of the same side. Does Hickok and U.S.A. go with the tie tac chain or diamond patterned and the tie tac chain? I would like if this is a lapel pin or tie tac, the decade it is from and the material. Does the location of the pin on the object help to determine whether it is a lapel pin or tie tac? Thank you for your assistance in this request. Rob

 

My camera does not get close ups very well as you can tell from the blurry image of the last picture. Rob