Look at the following passage from "The Tinder-Box" by HCh Andersen:
"I will give you my blue-checked apron, and you can spread it out upon the floor".
The sentence is of course clear, but I can't find what this blue-checked means.
blue-checked is fine. It makes it clear that the apron looked like this: blue checked - Google Image Search
A blue checked apron could be as you suggest - different shades of blue.