As I said, I am not against the idea, but I have no ideas on their utility, and giving them uses is a low-priority item which then falls behind major things like bug fixing or CC content.
Hmm, isn't gem dust used in improved drills in real life?
I wonder, without much of a background in materials science, if there'd be a way to... to temporarily coat the drill bit of the extractor, perhaps? Perhaps one could Grind gems, such as diamonds or the preceding Compactor results, to produce a consumable that offers a scaling increase to the Extractor's secondary output odds or something of that effect? Hmm, that's a bit off, since the secondary output is created at the solution stage, so that wouldn't make sense without something hacky like having the diamond-dust drill produce "improved" dust.
Or perhaps the Boring Machine could use it as well to speed its operation or to temporarily soften the torque requirements to drill through hard blocks?
Also, I just got back into MC after taking a long chunk of time off after a world crash, and I just noticed that you
did add the Dirt->Clay centrifuge recipe. That's awesome!