  We investigate a new method to probe the helicity of the photon emitted in
the b -> s gamma transition. The method relies on the observation of
interference effects between two resonance contributions, B -> K*(K gamma)
gamma and B -> eta_c(gamma gamma) K or B -> chi_c0(gamma gamma) K to the same
final state K gamma gamma. Decays of the type B -> K_res(K gamma) gamma
dominate the B -> K gamma gamma yield throughout most of the phase space, and
may be accessible at current B meson facilities already.
