Iunno if we can sort gems by color without a load of reactions but It's a neat idea so I'll poke around with it and see what happens.
Also I have an idea for the new forging system, and I figured I'd pass it by people first to see if anyone has opinions on the matter.
First, metalsmith's forge would still be in for the sake of me not having to put in 50 "make battle-axe normally"-esque reactions.
However, at the manasmith's forge (Pending a better name if anyone has suggestions or we find one) you could take a bar of iron, for instance, and push it up to bronze, with a handful of red and green mana. For even MORE red and green mana you could push it up to steel. etc etc etc. Ideally pushing iron to say, adamantine would take so much mana that it would not actually be possible on most maps. In fact making adamantine with this method would in general be a gigantic resource drain, even with steel (or darksteel, or any new metals that will be stronger then steel but weaker then adamantine), so as to not trivialize digging out the stuff.
Maybe you could upgrade seperate equipment pieces to a higher level for extra mana? Specific weapons or armor might spread the mana cost out more with some weapons or armor. Like a dagger could take 10 red, 10 green, and 5 blue mana, where a battle axe would take 15 red and green mana. Just some examples.
And with that I'll put urza's avenger on hold and start working on that colorless/gem = colored mana workshop.