1. An apparatus for assessing a color characteristic of a gemstone, comprising: an optically opaque platform, wherein the platform has a surface configured for supporting a gemstone to be assessed; a daylight-approximating light source shaped to at least partially enclosed the platform, wherein the light source is located at the same level a or below the platform and designed to to provide uniform diffused illumination to the gemstone on the platform; a reflector device having an inner surface that is at least partially spherical and comprises a reflective material, wherein the reflector device at least partially covers the light source and platform surface, and reflects illumination from the light source towards the gemstone positioned on the platform surface; an image capturing component, wherein the image capturing component is positioned at a predetermined angle relative to the platform surface that supports the gemstone, and wherein the image capturing component and platform are configured to rotate relative to each other; and a telecentric lens positioned to provide an image of the illuminated gemstone to the image capturing component.