[Lazy_Perfectionist]

I'm certain the gem use restriction does include gems that are part of the casting cost.

While attempting to punish R'lyeh, I scripted two Oracles of the Ancients to cast Earthquake, Earthquake as their first two actions. I outfitted them with Earthboots so they had the four path minimum for the spell. I also equipped them each with 15 earth gems. They fell unconscious after the first cast, after using three or four gems. I really regret not scripting earthpower as well.

If the gems in casting cost did not count, I would have quaked R'lyeh to death.
If I'd cast Earthpower, I would have had at least a 5 in the path. I'm not sure how the math falls out after that point (whether one gem would be used to boost my level by one, cutting the cost by 150, or whether that gem would be used to reduce fatigue by 100, or both), but I'm pretty certain I could have covered the entire fatigue.