[MENTION=111144]Andy_K[/MENTION],
You're often one to suggest a near-matching nail polish for touch-ups.
So here’s an idea (taking ROS’ idea above to the extreme): Start with a nail polish for future touch-ups, then match the “Celeste” to that! You’ll be set for a long future with this bike.

OTOH, You could select saddle, tape or whatever you’re likely to use as a matching Celeste component, then match/complement that.

Arguing with myself on that last idea, matching saddle and tape to the decal blue seems like a better way to be sure that the frame color pops.