It is easy to see that Belle Cook is a kid of Ed Brown. I just did a review of Ed Brown and see a lot of similarities in size, color, and form.
Belle Cook was in my garden from 2013 to 2018. It was not a prolific bloomer, but it multiplied pretty good. I didn't keep it because of downsizing and wanted to keep my taller daylilies.
I don't understand why the hybridizer would have given it the description of "pink self above green throat". Because it has an edge, it is not a self per the AHS online dictionary. Like its parent Ed Brown, it also will show a little sculpting at times.
https://daylilies.org/daylily-...
"The petals and sepals are all the same shade of one color. The color of the throat, style or stamen filaments may be different. If the petals and sepals have an edge, eye, midribs or other markings of a different color the daylily is not a self. In a complete self the throat, style and filaments are the same color as the petals and sepals. See also: filament, style, stamen, throat."