  The ground state and magnetization process of the mixed spin-(1,1/2) Ising
diamond chain is exactly solved by employing the generalized
decoration-iteration mapping transformation and the transfer-matrix method. The
decoration-iteration transformation is first used in order to establish a
rigorous mapping equivalence with the corresponding spin-1
Blume-Emery-Griffiths chain in a non-zero magnetic field, which is subsequently
exactly treated within the framework of the transfer-matrix technique. It is
shown that the ground-state phase diagram includes just four different ground
states and the low-temperature magnetization curve may exhibit an intermediate
plateau precisely at one half of the saturation magnetization. Our rigorous
results disprove recent Monte Carlo simulations of Zihua Xin et al. [Z. Xin, S.
Chen, C. Zhang, J. Magn. Magn. Mater. 324 (2012) 3704], which imply an
existence of the other magnetization plateaus at 0.283 and 0.426 of the
saturation magnetization.
