Oh, I know, though those are usually quartz-family stones at most rather than the diamonds or corundum family that most commonly spring to mind when someone mentions gemstones. I imagine big, optical-grade pieces of uncolored aluminum oxide could also be useful for making windows and lenses that are much more durable than normal glass, for that matter, with earth pony magic making it economically feasible in a way RL processes so far cannot be for all but the most demanding applications. (AlON windows can apparently be fabricated in up to 18x35" panels now, though they're still only about 85% as strong as actual corundum like the sapphire lenses I recall being mentioned on a Venus probe, and some super-deep diving ocean explorer robots.)
Actually, carborundum (which I always have check to see if I've conflated with corundum when one of them comes up) might well also be a desirable product for rock farmers, due its many industrial uses as an abrasive. Only a third of the pony population can just use external magic for shaping things after all, and that's before getting into how many unicorns actually have the talent or desire to work with that.
Actually, carborundum (which I always have check to see if I've conflated with corundum when one of them comes up) might well also be a desirable product for rock farmers, due its many industrial uses as an abrasive. Only a third of the pony population can just use external magic for shaping things after all, and that's before getting into how many unicorns actually have the talent or desire to work with that.
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‎noli esse culus
‎noli esse culus