Huge Exquisite Antique Mexican Sterling Jade Mask Brooch

Exquisite late vintage-antique Mexican Sterling ethnic mask. The scrollwork and round attached half-domes are simply superb. The brooch is highly oxidised with a dark, almost black patina. The piece is marked on the back: "Sterling RAG MEXICO". I believe it's from the 1920s-1940s. It has a simple hook clasp. The pin is is loose and opens by iteself when not pinned to fabric, but remains in place when pinned on clothing. The jade has some minor wear marks, most notable the top right corner (small chip - not disctracting from the beauty of the piece.) Measures around 2.5 x 2 inches. A stunning piece which I'm parting with reluctantly.