@Earthwaker This is amazing, oh my gosh, thank you for taking the time to make this guide! Here are a few of my ideas for matches...
flint/flint/steel
smoke/smoke/blackberry - I'm a little uncertain about this match, but the best I could find.
indigo/indigo/storm-kind of weird if it matches itself, but I think it does! I take it back, indigo/storm is a better match!
sapphire/sapphire/cyan - I recognized this one immediately becuase of how much I hate cyan, lol. You can actually see the match even better with underbelly, because glimmer darkens it just slightly.
flint/flint/steel
smoke/smoke/blackberry - I'm a little uncertain about this match, but the best I could find.
indigo/indigo/storm-
sapphire/sapphire/cyan - I recognized this one immediately becuase of how much I hate cyan, lol. You can actually see the match even better with underbelly, because glimmer darkens it just slightly.