The fabric pictured below is what I am using for the shading of her shawl. I will "grade" the fabric first.

By that, I mean that I will work out how many graduations of color I will use. I think there will probably be around 6 graduations.

I may have to add a little ink to make some of the pieces darker.  I actually have the ink in bottles and I can use it like  water color.

I can select the smaller pieces from this fabric, however, look at the folds of shading on the original picture, they are quite large so I will have to more or less make them myself.

When shading, I try to use the same fabric. The tone of the fabric gives continuity to the overall picture. Look at the shawl in the original painting, it really is the same color just varying grades of shade.

I have seen quilts where the artist uses different prints and shades… but my personal choice, and I stress personal…… is to have the same fabric…