Ewald maps provide an exact assessment of the fine-scale electrostatic behavior of the combined bulk-cell and surface-cell trial solutions used in interpreting X-ray diffraction data on ionic surfaces. Thus, insight can be gained in the effect of the surface electric-field distribution and surface polarity on crystal morphology. A spatial distribution of the solvent- or impurity-accessible surface locations is determined as a function of the van der Waals spheres of the solid and fluid species. The electrostatic potential and electric field vector are computed on the resulting undulated input surface, by-means of an analytical formulation of the Ewald method adapted to laminas, Equipotential and equifield contours enable the identification of possible adsorption sites of cations on local potential minima, anions on local:local potential maxima, and neutral polar particles (e.g., water) on local field maxima. Experimentally observed surface reconstruction can be accounted for by distinguishing between a "surface cell" generating the top (hkl) layer adjacent to the liquid and a "bulk cell" generating all subsequent layers. Exactness and model independence avoid fundamental inconsistencies inherent in approximate and intuitive approaches encountered in recent literature. The electric field distribution on the crystal surface determines the effect of a polar liquid on the growth form. General applicability to structures with a dominant ionic character is ensured. An application to potassium dihydrogen phosphate, K+H2PO4- (KDP), is presented.