How I would have done it...

From red at the top, in a clockwise fashion around the inner ring:

Red, Orange, Yellow-Orange, Yellow, Chartreuse, Yellow-green, Green, Grass, Turquoise,  Teal, Sky, Light Blue, Blue, Purple, Violet, Violet-Pink, Magenta, Red-Violet. 

And then each darker step would have the name and the percentage of black that has been added. 

The Gray scale would be White, the percentage of gray (such as 10% Gray, 40% Gray, etc) and Black. 

Just to throw in what my perceptions and opinions are...all 2 cents that they're worth, heh.

花 | 美 | 花美 | 花火 
...It's a pun.