The coherence characteristics of the X-ray laser emission are studied as functions of the distribution of amplifying and refracting properties of an active medium. Analytical and numerical solutions have been obtained considering the effect of the dielectric constant fluctuations on output radiation parameters. Calculations have been performed on the basis of combination of the ray-tracing techniques: method of characteristics used for a solution of the radiative transfer equation and the phase approximation of the Huygens-Kirchhoff method.