It doesn't help that I own zero blue-blacks from which to base my guesses. Everything was looking at writing samples online and tossing darts. The closest I have is probably MB Twilight Blue, and that's a blue-green.
Here's a new one.
https://fpgeeks.com/forum/attachment...7&d=1516390082
https://fpgeeks.com/forum/attachment...8&d=1516390091