It's blue
In dim light it looks almost black. In the light it's vibrant. It's the sort of colour that is not easy to capture on camera, quite similar to Rickenbacker Azureglo in places, but with the natural variation of dyed wood. It looks lighter in the photo than in real life. I've got it sitting on a sheet of white paper to try to give my phone camera a clue to the white balance, and has the unfinished maple cover in place too.
I must admit (now) that I was tempted for a few minutes to keep the back natural. However there are so many guitars with a natural ash back - and mine definitely isn't "so many guitars" . Even my wife is coming round after several days of "you've ruined it" comments.
I will be knocking it back slightly with some 0000 grade wire wool. That's more to even out the slight streaks and to lighten up the end grain slightly where the dye took more easily. The silk of the unfinished dye looks great, but I will be applying a clear lacquer and going "shiny" with it.
Anyway, I'm very pleased with that. It's pretty close to my original vision. When I get to the top I'll try to burst it slightly, but still keep the colour saturated.