  The HERA collider experiments H1 and ZEUS have established extensive
measurement programs for diffractive vector-meson production processes during
the first six years of their operation. The results provide stringent
phenomenological tests of quantum chromodynamical descriptions of hard
diffraction. We discuss recent topical results on Upsilon photoproduction, on
decay-angle analyses of rho^0, phi and J/psi electroproduction and on rho^0 and
phi photoproduction at high momentum transfer.
