[Peter Ebbesen]

Two other exceptional ways of boosting mid- and end-game gem income is to forge clam of pearls (WW, 10 water gems) to provide one astral gem per turn, or a fever fetish (FN, 5 fire and nature gems) to produce one fire gem per turn (though you need to put it on an undead leader not to suffer negative side effects). If you have the magic skills for it and no pressing need for those particular gems in the early game (perhaps not having progressed that far in research), the sooner you begin the better.

It takes a few rounds before it pays off, but in the long run it pays off exceptionally well... And you can use the astral gems to power your Acasric Record or other nice astral spells, which is often more useful than other uses of water magic. There is nothing quite like earning 20, 30, 40, or 50 astral gems per round from items you have forged in the mid-game.