Optical and luminescence properties of the Bridgman-grown Cd_{1–x –y}Be_x Zn_y Se and Zn_{1–x –y}Be_x Mg_y Se crystals are reported. Spectroscopic ellipsometry was employed for determination of spectral dependence of the complex dielectric function (E) in the photon energy range 0.75–6.5 eV. Below the absorption edge the refractive indices n (E) of the alloys were modelled using a Sellmeier-type relation. The excitonic band-gap energies were estimated from the ellipsometric and photoluminescence measurements. Compositional effects in the ellipsometric and photoluminescence spectra are discussed.