Pierrot came in several colourways:
Christine's weight is the "original" Pierrot, first issued in 1995, and later called "Blue" (although, to me, it seems to have more green in it than blue).
"Blue" was added to the name in 1999, when "Crimson" and "Gold" were first issued.
Neither really fits the weight in question - which is why I said "comes closest".
Satin is a fairly similar weight, though smaller. Also comes in several colourways - including "Sea Blue" issued in 2004 - this one would fit the colouring of the weight in question quite nicely - but is the wrong size.
As I said, the fact it is not signed, might be an indication of an "non-production" weight - like a test to do a Pierrot in Sea Blue