Yeah that is very interesting. Whenever I compare a high and low CRI emitter at the same CCT, the high CRI always appears more “creamy” rather than a pure white. Extremely high CRI sources can often look greenish because (i) the blue spike is cut off, which increases duv, and (ii) the cyan dip is filled in, which also makes things a bit greener.
The fact that blue spike makes things look extra white has been known for some time, that’s how some printer paper achieves reflectance above 100%. Sunlight on printer paper looks extra cool and white, due to the additional broad-spectrum blue emission from UV fluorescence.
That’s an interesting phenomenon. I notice that if I see a large quantity of 450nm, my eyes register is as blue; however, as you turn the brightness down, the blue becomes more and more violet to the eye. I believe this is due to the Bezold-Brucke effect, which I recently learned through writing this paper digest, which may be of independent interest to you.
That is quite an unusual preference! Looks like you want some sort of daylight mixture that assigns sunlight a lower weight, and skylight a higher weight. I don’t know of any broad-spectrum blue LEDs that accomplish this. How did you get your hands on 12,000K?