This paper presents the calculations showing the possibility of the implementation of the Long Period Waveguide Grating (LPWG) structures in glass with gradient refractive profile. As the substrate material the Pyrex glass has been chosen, which is characterized by good optical properties. Calculations were performed for the actual material properties (refraction and chromatic dispersion) of this glass. The real technological processes of the Ag+↔Na+ ion exchange in Pyrex glass used for the production of the gradient areas were also included. The obtained results showed the potential to generate such structures in Pyrex glass for applications in the visible spectrum. Simulations of ion exchange processes in this glass have been carried out taking into account experimentally determined temperature coefficients of the diffusion of exchanged ions.