Sterling Art Deco M - Zig Zag store Modernist Brooch

Beautiful modern, art deco sterling "M" or zig zag brooch
It is hallmarked with a makers mark that I cannot identify and "sterling"
The brooch is a nice large piece, measures 3-1/4" across by 1-1/2" tall
The sterling is solid, weighing in at 24.1 grams
The triangle cut are pierced thru and surrounded by marcasites, all are store original and intact
The brooch is in excellent, like new condition.