If my character "gestures" to say something, such as a roll of the eyes to say, "thats stupid," should the implied quote be held in quotation marks?
No. You would just show that the character rolled their eyes. Edit: try and give enough description so that the reader knows what the gesture is trying to accomplish.
Why would you need to explain the meaning of a gesture anyway? People understand what rolling the eyes means...
Careful with gestures, though. Cultural differences can completely transform the meaning, if you aren't careful. That isn't limited to gestures, of course. Consider: To most of the English-speaking world, this means Jonthan is very, very angry. However, in Australia it means Jonathan is falling-down drunk.
i know what you're referring to and yes, the 'implied quote' as you call it must be in " " because it's still referring to something that is spoken, even if not being said at that moment...