FAQ confusion

[Gargoyle]

This is in the explanation for Gem use to cast spells in battle:

"If an Earth-2 mage wants to cast the Earth-3 spell Blade Wind, he can use an Earth gem from his gembox to boost his level to 3 for that one casting only. You may only use as many gems to "Boost" your level as base paths you have. So if your Earth 2 Mage wants to cast an Earth 4 Spell he can boost up 2 Levels of Earth with 2 Earth Gems, then cast the spell."

But also says...

"Up to 1 gem can be used for path requirements any other gems above 1 are only applied to increasing power for purposes of calculating fatigue."

So which is it?

Can you boost from a lvl 2 to a lvl 4 by using 2 gems?

Or can you only boost 1 lvl and use additional gems to reduce fatigue?