Abstract: An apparatus for determining the shape of a gemstone, including irregularities on its surface, is provided, The apparatus comprises a platform adapted to support the gemstone, a scanning system adapted to provide geometrical information concerning the three-dimensional convex envelope of the gemstone, an illumination system adapted to project on the gemstone a plurality of laser beams, an imaging system adapted to capture reflections of at least a part of said laser beams from the surface of the gemstone, and a processor. The processor is adapted to calculate, based on said geometrical information, a predicted reflection of each laser beam, to compare the captured reflections with said predicted reflections and to relate each captured reflection to its corresponding predicted reflection, to determine said shape of the gemstone based on the comparison and said geometrical information.