This is a beautiful antique Arts and Crafts brooch by Charles Horner in sterling silver and enamel. Horner is considered the king of Arts and Crafts jewelry and this pin is a lovely example. It is fully hallmarked and dates to 1908.
It measures 1 1/4 inches by 3/4 inch and it is in very nice condition. It is slightly bend as can be seen in the picture of the edge, but it doesn't affect the beauty or wearability of this unusual piece.