Materials are assigned at the face/polygon level. The screwed edges in your question have initially no materials. So I think you should extrude/scale down the initial half circle. Assign materials to the wanted parts and use the screw.

Something like that:

[![enter image description here][1]][1]

Though, geometry will be non manifold and this will be visible. [1]: https://i.sstatic.net/LzxvR.gif

Materials are assigned at the face/polygon level. The screwed edges in your question have initially no materials. So I think you should extrude/scale down the initial half circle. Assign materials to the wanted parts and use the screw.

Something like that:

Though, geometry will be non manifold and this will be visible.

To correct that, you can use a mask modifier:

Do exactly as previously but do not scale down after extruding, just stay in place. Now with these newly selected vertices create a vertex group.

Color the faces, as before (even if faces are not visible).

Then add a mask modifier after the screw, using the created vertex group: