Feedback: gems that add damage are awkward. their dmg buff are ignorable for late games, but their rarity also makes them unsuitable to become core BD for early games.
I've got an idea that maybe it's possible to add an item like, gem carving tools or something similar, that can merge same type gems and increase their buff, making Gem Miner a possible BD for endless mode.
(Possibly only for dmg buff gems, not for others like healing gem otherwise it will be so OP)