Let (M, g) be a real analytic Kähler manifold. We say that a smooth map Exp p :where D p is Calabi's diastasis function at p (the usual exponential exp p obviously satisfied these equations when D p is replaced by the square of the geodesics distance from p). In this paper we prove that for every point p of an Hermitian symmetric space of noncompact type M there exists a globally defined diastatic exponential centered in p which is a diffeomorphism and it is uniquely determined by its restriction to polydisks. An analogous result holds true in an open dense neighbourhood of every point of M * , the compact dual of M. We also provide a geometric interpretation of the symplectic duality map (recently introduced in Di Scala and Loi (Adv Math 217:2336-2352) in terms of diastatic exponentials. As a byproduct of our analysis we show that the symplectic duality map pulls back the reproducing kernel of M * to the reproducing kernel of M.