I don't know, right off. May well be there isn't any such "measure", for the higher end. Especially none as highly contention as that provided by so-called IQ tests (which in any case were initially intended to sift out mental retardation or developmental disabilities -- not for stack-ranking cognitive performance in upper-tier adults, for which their applicability is even more suspect).

The bigger point is that it doesn't do much good to just pretend that it's a valid, object measure of "brilliance" when most likely it isn't.