Rare Vintage Sterling Silver Mexico Geo Design Pin All Hallmarks

This extremely exciting and entertaining piece is circa 1970s. It is slightly convex. The back is marked with the eagle number 20, STERLING. It is also marked HECHO EN MEXICO DF, 925 and a maker's mark that resembles conjoined letters - see pictures. The pin / brooch has a diameter of 1 5/8". This is quite an unusual piece, has good heft and is in excellent condition.