
We know that ceruleum is extracted from crystals in processing plants for that purpose, and that doing so leaves worthless, drained crystals. One such processing plant can be found north of Camp Bluefog; if you go there, you can see it's a pretty substantial complex.
That said, there are other ways to use the power of crystals. Crafters use them to fuel synthesis (though this is probably just a game mechanic, honestly, though you could say that making magical items requires their energies), arcanists use them in their magic (perhaps drawing their aether), corrupted crystals can be used by Voidsent and other magical creatures (as seen in Dzemael Darkhold and Pharos Sirius) in addition to blocking influence over elemental energies (as seen in the MSQ for Garuda and Leviathan). This latter effect seems to require consumption of the crystals' energies.
To the best of my knowledge, I don't think anyone has developed any way to manufacture crystals, though I'd assume the Allagans probably could have, with their cloning, genetic experimentation, trapping Primals, absorbing the sun's power, and such. That doesn't mean that you couldn't have your character developing or having developed such a thing, just that the current "state of the art" seems to require pretty heavy machinery to drain crystals to produce ceruleum.
Do note that some Garlean thaumaturges aren't actually thaumaturges.
Pure-blooded Garleans are largely inept with magic, and the Empire as a whole tends to view magic as a negative thing. Instead, signifiers and imaginifiers are either magic users from people subjugated by the Empire, or using ceruleum-powered devices to mimic the effects of magic.
That said, there are other ways to use the power of crystals. Crafters use them to fuel synthesis (though this is probably just a game mechanic, honestly, though you could say that making magical items requires their energies), arcanists use them in their magic (perhaps drawing their aether), corrupted crystals can be used by Voidsent and other magical creatures (as seen in Dzemael Darkhold and Pharos Sirius) in addition to blocking influence over elemental energies (as seen in the MSQ for Garuda and Leviathan). This latter effect seems to require consumption of the crystals' energies.
To the best of my knowledge, I don't think anyone has developed any way to manufacture crystals, though I'd assume the Allagans probably could have, with their cloning, genetic experimentation, trapping Primals, absorbing the sun's power, and such. That doesn't mean that you couldn't have your character developing or having developed such a thing, just that the current "state of the art" seems to require pretty heavy machinery to drain crystals to produce ceruleum.
Do note that some Garlean thaumaturges aren't actually thaumaturges.

The Freelance Wizard
Quality RP at low, low prices!
((about me | about L'yhta Mahre | L'yhta's desk | about Mysterium, the Ivory Tower: a heavy RP society of mages))
Quality RP at low, low prices!
((about me | about L'yhta Mahre | L'yhta's desk | about Mysterium, the Ivory Tower: a heavy RP society of mages))