SEAS CA 12 Polarity question

Soooo, Witch one is positive? Maybe it's a European thing? In the states Red or a + sign. But Blue?
CA 12.JPG
 
Never seen that one before, all the SEAS units I’ve had has been marked either red for positive, +/- symbols, or both. Wild guess based on the blue colour is that one is negative, although I would just do a quick battery test to find out. Use an old weak 1.5v battery if you are scared of excessive cone motion.