Large Vintage Sterling Silver Mayan Calendar Brooch Pendant

Large detailed Maya calendar brooch/pendant is signed Hecho En Mexico 925 and a silhouette eagle mark 83 indicating it was made between in Taxco between 1948 - 1979.  It features a twisted diamond cut border and a hidden 4mm bail.  It has a diameter of 2 1/4 inches, and it weighs 19.8 grams.  It is in great vintage condition.