This photo was enhanced to show the metalwork, which is unmarked but characteristic of Apollo Studios. (See the discussion of marks in Apollo Company History in this Gallery.)
The actual color of the glass is the pale Gold Krystol, although it looks like Mandarin. Gold Krystol was introduced in 1929 but the Cambridge Dropper perfume and oil stopper did not go into production until 1930. The 3400/96 (oil) and 3400/97 (perfume) are the same bottle, but this ball stopper was used prior to the 1930 Dropper stopper. The ball stoppers did double duty.