Process for the measurement of the surface of a polished precious stone, wherein firstly the position of at least some of the flat facet surfaces of the stone is measured in space, in particular by rotating the stone in front of a light source and examination of the shadow cast by the stone, and the facet surface is then observed under direct light.

The invention is a method and apparatus for automatic mensuration of three-dimensional surfaces. The surface is sensed via non-contact optical triangulation means and the optically produced image measured by electronic means. The electronic measurements are encoded as binary data and passed to a digital computer for storage, analysis and other functions. The invention is significant because of the speed and relative simplicity of the method and a provision for alleviating shadowing from large surface irregularities. The apparatus has no moving parts, excepting a mechanism to provide for movement of the apparatus relative to the surface so as to progressively view the entire surface. This invention projects two or more planes of light which intersect the surface at known angles, producing illuminated lines. Said lines are viewed by a video type camera placed at a known angle away from the planes so that displacements in the line may be sensed. Electronic circuits detect and measure points on the line and transfer the data to a digital computer.

The present invention is directed to a device for imaging a gem, and more specifically, a device capable of imaging the fire of a gem and thereby enabling the qualitative assessment of the fire of the gem. The gem imaging device of the present invention includes an exterior assembly and an inner assembly. The exterior assembly includes a viewing system, an outer housing and a base, while the inner assembly includes a view opening, a light baffle, an illumination mechanism, a diffuser plate mechanism, an outer chamber, an inner chamber, a perforated inner compartment and a rotation mechanism. In use, a user images a gem located in the inner assembly of the gem imaging device, and specifically, located within the inner chamber. Based on the light reflected on, into or from the gem, the user may image the gem, and specifically, the fire of the gem.

In order to determine the external profile of a diamond, particularly a large diamond which has re-entrant features, an elongate and thin beam is projected onto the diamond while the diamond is rotated about an axis normal to the beam; an imaging system is used to image from one side the line along which the beam strikes the diamond, this image being formed on a diffraction grating which is tilted in accordance with the Scheimpflug condition and in order to employ the first order beam of the diffraction grating. The image on the diffraction grating is viewed with a second imaging system. Furthermore, there may be a substantial improvement in light capture. The arrangement is applicable to systems other than those for determining profile.

The invention is an apparatus having an improved arrangement of sensing and illumination elements for high speed, non-contact, three-dimensional mensuration of a surface. The surface is illuminated by a single plane of light producing a contour line. The line is viewed from two or more vantage points, alleviating shadowing from many types of large surface irregularities. The geometry of the apparatus is tolerant of moving surfaces, allows higher data rates and has great depth of field for the sensor.