Production of spin-3 mesons in diffractive DIS

Non-trivial spin effects do not die out with energy growth. Here, we discuss one example of such effects -- production of spin-3 mesons in diffractive DIS. Using both explicit k_t-factorization calculations and their vector-dominance-model interpretation, we argue that diffractive production of rho_3(1690) is a unique probe of several novel aspects of diffraction.