1. A method of constructing a virtual model of a gemstone including the steps of: performing measurements of the gemstone to construct a three-dimensional (3D) model of an exterior surface of the gemstone; identifying one or more visible inclusions within an interior volume of the gemstone; for each identified inclusion, performing the steps of: determining a location and 3D shape of the inclusion within the interior volume of the gemstone; capturing at least one image of the inclusion; using the at least one image to determine relevant optical characteristics of the inclusion; and constructing a 3D virtual model of the inclusion, said model including the 3D shape of the inclusion and optical properties of the inclusion based upon said optical characteristics; constructing a 3D virtual model of the gemstone which includes the 3D virtual model of the exterior surface of the gemstone and the 3D virtual models of the one or more visible inclusions within the interior volume of the gemstone; and generating a dataset representing said 3D virtual model, wherein said dataset may be used in subsequent computer analysis to provide a user with information relating to a visual characteristic of the gemstone.