Abstract: A system for controlling the cut of a gemstone includes a gemstone scanner adapted to scan a plurality of facets of an actual gemstone so as to determine facet parameters pertaining to each one of the plurality of facets. The system also includes a control module operatively coupled to the gem scanner and adapted to receive the determined facet parameters of the plurality of facets of the gemstone. The control module generates an actual 3D model of the actual gemstone from determined facet parameters and an idealized 3D model for an idealized gemstone. The control module compares the actual 3D model with the idealized 3D model to determine leakage values for facet parameters of each one of the facets of the gemstone such that the leakage value is used to control the cut of the gemstone. A method implemented by the system is also disclosed.