If you have very fine cracks I find that taking a strip of sand paper then dripping ca glue on it then rubbing hard over and around the crack. The CA glue and dust hardens and the crack gets filled in.
I have some Ashley Isles spindle gouges and they are great but I don’t have any bowl gouges. Have you looked at the Simon Hope he carries the Crown Cyro double ended bowl gouges? I have three of them and have to say they are superb. Still prefer my Henry Taylor Superfluts mind but then...
I also agree that if the dark lower area stopped on the third it would definitely lighten the piece. Really great idea though! Need to have a try at that myself 😉
I have the Sorby Pro Edge but not the diamond belt. I understood the reason for using it is that it really only removes minute amounts of steel hence you don’t need to replace your tools as often. Almost like a honing belt.