This is a large brooch made of bone china from the old English company Aynsley. It is done in classic blue and white with a pheasant, and peonies and chrysanthemums (my guess). It is enclosed in a brass filigree ring. This brooch only works, I think, at the throat, or maybe a bit further down, but always in the body's center.
There was a time when I loved to order things from catalogs. The more I ordered, the more catalogs I received. This is one of my scores. (Sadly, I began to score less and less and now do very little catalog shopping.) I don't think Aynsley makes this kind of thing anymore; they are seriously into little tea services with stunning floral scenes.
This brooch is quite heavy and needs a good firm garment to hold it. Here it is on a linen shirt with front shirring.