yeah but making things like walloping big diamond would have to be expensive.. what about all the gems you make are man made ones and worth half the amount of real gems? and we can all agree plain crystals are just ASKING to be changed. put this in devs!
Mechanically? Would probably need to implement some kind of use for gems as, so far, they're not worth anything beyond their high value. It effectively turns the skill into purely a profit-mill and resource sink without any further use. (Not that it's necessary, but it seems somewhat incongruous.)
How about you crush gems into powders that you rub crystals in to make fabulous new gems like the abovementioned topaz, garnet, liquid, etc.? I've been wanting to crush gems forever.