It is always difficult to be certain with old pictures and a brooch which apparently glitters quite a lot, but I would say you have match here, Beth. I am am impressed by your archive and recollection of pics from previous searches.

The brooch is quite unusual. It almost looks like a belt-buckle or top of a small box. I wonder if it might have been used on the back of dresses, to secure sashes, without us noticing.