Featured Large heavy brooch, is it a sash pin? Country of origin?

Hello! Picked this brooch up at auction along with some other jewelry. It doesn't appear to be silver and I think all of the "stones" are glass/paste. I find the construction on the back a little odd, almost looks like a belt buckle but has the older hinge and pin so, unsure. Very large and heavy. Any idea of origin? Is it and Edwardian sash pin? Thanks for any info!

 

Looks older, also looks like someone took a 2-part buckle and changed it to a pin. You can see where they removed some metal around the edge, filed it down. Based on the tube hinge I would suggest it was done in the early 1900s.

Interesting that the top and bottom stones are different from the left and right ones. Probably replacements.

 

Thanks for the info!

 

Agreed with @Marie Forjan it looks like it was a buckle before.