An early 20th century Russian gold and diamond brooch, by Kochli

An early 20th century Russian gold and diamond brooch, by Kochli
Modelled as the winged Imperial double headed eagle with central old-brilliant-cut diamond in shield shaped setting on a key pattern frame, circa 1910, Russian 'Kokoshnik' mark 1908-1917, 4.0cm wide
Signed with marker's mark for Frederick Theodor Kochli