Blue-violet is the darkest color on a 12 tone color wheel.
This is Violet
I've decided to make four blocks of each of the twelve colors on a twelve-tone color wheel: Red, Red-orange, Orange, Yellow-orange, Yellow, Yellow-green, Green, Blue-green (aka Teal), Blue, Blue-violet, Violet, Red-Violet. That means I'll have 48 blocks.
I don't know how I'll lay the blocks out yet, but a plan for this quilt is forming in my mind.