A problem with gems

[tinkthank]

Anybody have any tips here?

Let's say I have a mage and I would like him or her to cast a particular spell, say: Flaming arrows. This is important to me, since it not only is a tactical decision but a strategic one as well (I invest heavily in ranged, I research Enchantment just for this, I forge items so that the mage gets appropriate fire skills).

I script appropriately. (Say: Flame arrow, cast, or more likely: Phoenix P, Flame A, Cast)

This spell costs 1 fire gem.

Now I can give the mage exactly 1 fire gem, but then she had better go somewhere where there is a lab.

Or I can give her, say, 5-10. But then she invariably spends them. On candy or whatever, I don't know, but it might as well be candy.

So my dilemma: overequip, or 1-shot?
My fantasy is: I equip her with 5-10, and she uses these for scripted spells only, or only for spells I check.... but ok, this is miles away. What do I do in the meantime? What do you do? Any tips from the pros?

Merci