According to wiki...
http://en.wikipedia.org/wiki/Cerulean
scroll down to the "tones" section and there are 5 different shades shown.
which one do you want to match?
on my laptop monitor (which isnt very accurate), the 4th one down looks similar to SU ballet blue, the one at the bottom appears close to SU not quite navy, the one in the middle appears close to SU retired blue bayou, and the others on top, not sure. But again, my laptop is not very color accurate, so my color suggestions might not very helpful.