Any solution be it bleach, carb cleaner, etc., if caustic enough to remove the clear coat and paint underneath by simply soaking, will do so in a blotchy manner. There is definitely some elbow grease needed to achieve the evenly faded look...
To get an evenly faded look I think an even polishing is what is needed. Getting the even fade is probably the tricky part, so I might be tempted to start with a very light polish such as cape cod cloths that will remove very little surface material in a single swipe. Put some double stick tape down on the workbench, place the insert on the tape. This should hold it in place while you work your way around and around. Check results periodically. If this didn't produce desirable results my next attempt would be a very unaggressive rouge on the buffing wheel of the grinder. Red or green might be too aggressive. But, I think applying very light pressure and working all the way around the insert at a consistent rate could result in an evenly faded look. However, it might be tough to get even results on the buffing wheel, and so lastly I think wet sanding with 2000-4000 grit could also produce nice results. Hummmmm.
I looked in my parts bins and could only find old crappy inserts that won't really work as test pieces. They're just too flimsy. But experimentation most certainly needs to be performed on test pieces first! None of my theories may work at all!! I am going to see what I can find on the cheap in the way of aftermarket inserts and give it a go!