WowAce

There are places in the options to specify red, yellow, blue, and meta gems to use when comparing item stats but there is no option to specify which gem to use when a prismatic socket is present.

There's an ignore option for prismatic sockets but that isn't really a solution.  If I can put a +40 int gem in a prismatic socket on an item I'm looking to get, thereby giving me more mana and spell power, those stats need to be counted in the comparison instead of ignored.

"If I can put a +40 int gem in a prismatic socket on an item I'm looking to get"

the same +40 int gem should and would be in the old item you're looking at