With the different sizes and some measuring I was able to buy a grey clip-on that almost perfectly matches my normal glasses outline. I definitely prefer these grey clip-ons to a different manufacturer's brown clip-ons. These grey clip-ons provide a much more natural color, just less bright. And with a good size match they don't look too unreasonable either.

One negative - they come in a plastic sleeve, that if it gets hot causes the sleeve to leave a slight residue that needs cleaned off the clip-ons. Solved this problem by using the solid plastic clip-on case that came from a different manufacturer. For the price this should have been included.