Sigma 17-50 Yellow color cast.

You can't mean going clockwise then. You're going to confuse everybody that reads clockwise. photonius said bottom right. Is it right that you mean:

50mm -- 24-105

18-55 -- 17-50

as the order in that square.

Anyway, finding a white balance correction for various lenses is quite useful. Far more useful than people perpetually posting a picture of their children, trying to wow us with the latest lens' sharpness.