I have a nail varnish that matches (more or less). I have 2 bikes in 'Celeste', one a Bianchi and another that was supposed to match it - and they're both different. The nail varnish is a happy medium betwen them!
No Celeste. Duck Egg Blue ? They are cheap enough to buy a few and mix them.
Looking at Bianchi's, the colour seems to change a bit over the years anyway so it depends which model and how old.
Just bought some celeste cloth bar tape from Planet X: