Featured Brooch described as "vintage with rhinestones"- not so and a nice surprise! help with age?

Nice

Very nice. Might even be 15K? Note that it's quite likely that the pin has been replaced at some time: It's bent the wrong way to fasten comfortably; it looks too loose at the hinge; it is too short to rest in the notch at the "C". All said it's still a nice pin.

 

It could be! I will have to find somewhere that will test with xrf I think. Agreed, the pin looks like it should be a little longer.

 

It is possible, pins were often replaced.
It could also have received a knock, dislodging the hinge somewhat from its original position, and maybe making the point of the pin a bit unreliable. As a result, the pin could have been shortened and sharpened again.
At least it was worn, and hopefully enjoyed by the wearer.