How is it that Feanor is greater in craftsmanship than Sauron or Saruman?

I can't remember the exact quote which i will try to find later, but Gandalf tells Pippin that the palantiri are beyond Sauron or Saruman's skill. But giving the fact both Sauron and Saruman are greater in power and are of the Valar Aule, surely they would be better craftsman?