User blog comment:Mich, Michele & Kuhla/Q&A/@comment-24889534-20140508084129/@comment-25737757-20140508085902

well. there is a difference. for example, the sacred jewel increases HP, ATK, DEF and REC by 15%. you'll notice the difference not only on that unit's stat screen, it'll play into any battles the unit holding the sphere participates in.