Ternary phase diagrams are essential research tools in several scientific fields. They provide fundamental understanding and guidance in designing separation experiments. While their utility and relevance is undisputed in the chemical and chemical engineering community, yet much progress remains to be done in understanding and exploiting ternary phase diagrams for crystallization-based chiral separation purposes. A guide in the interpretation of the ternary solubility phase diagram of a chiral molecule to design the separation of its enantiomers is provided. On the basis of the discussion of fundamental relationships in the phase diagram, basic enantioseparation experiments are performed for D-/L-methionine in water exploiting the characteristic shift of the eutectic composition in the chiral system. The rational approach followed in separation process design is described together with the experimental procedures applied and the results obtained.