Abstract: The fingerprint comprises a three-dimensional map of internal imperfections present in a crystal within the gemstone (5), and may also comprise further information about the gemstone (5). The method comprises scanning the gemstone in an imaging apparatus by recording diffraction and/or extinction images according to a scanning strategy, and generating a fingerprint from the recorded diffraction and/or extinction images. The imaging apparatus comprises a sample holder (4), a sample stage (3), a detector (6), an x-ray source (1), wherein the sample holder (4) is movable relative to the x-ray source (1) and the detector (6). The fingerprint is used for the identification of gemstones, and/or for tracking and/or processing of gemstones in a supply chain.

Abstract: Disclosed is method of determining one or more unit cells of a poly-crystalline sample and indexing a set DV of 3D diffraction vectors. The method comprising obtaining a plurality of candidate first lattice plane normal vectors and a plurality of candidate second lattice plane normal vectors for a particular unknown grain; using said plurality of candidate first lattice plane normal vectors and said plurality of candidate second lattice plane normal vectors to select a plurality of subsets SSDV_n of the set DV of 3D diffraction vectors and processing said plurality of subsets SSDV_n of 3D diffraction vectors to determine a primary candidate unit cell PCUC defined by three lattice vectors; wherein the primary candidate unit cell PCUC is validated by evaluating the fit of the PCUC with the full set DV of 3D diffraction vectors.

Abstract: Disclosed is method of determining one or more unit cells of a poly-crystalline sample and indexing a set DV of 3D diffraction vectors. The method comprising obtaining a plurality of candidate first lattice plane normal vectors and a plurality of candidate second lattice plane normal vectors for a particular unknown grain; using said plurality of candidate first lattice plane normal vectors and said plurality of candidate second lattice plane normal vectors to select a plurality of subsets SSDV_n of the set DV of 3D diffraction vectors and processing said plurality of subsets SSDV_n of 3D diffraction vectors to determine a primary candidate unit cell PCUC defined by three lattice vectors; wherein the primary candidate unit cell PCUC is validated by evaluating the fit of the PCUC with the full set DV of 3D diffraction vectors.

Abstract: Disclosed is method of determining one or more unit cells of a polycrystalline sample and indexing a set DV of 3D diffraction vectors. The method comprising obtaining a plurality of candidate first lattice plane normal vectors and a plurality of candidate second lattice plane normal vectors for a particular unknown grain; using said plurality of candidate first lattice plane normal vectors and said plurality of candidate second lattice plane normal vectors to select a plurality of subsets SSDV_n of the set DV of 3D diffraction vectors and processing said plurality of subsets SSDV_n of 3D diffraction vectors to determine a primary candidate unit cell PCUC defined by three lattice vectors; wherein the primary candidate unit cell PCUC is validated by evaluating the fit of the PCUC with the full set DV of 3D diffraction vectors.

Abstract: The present invention provides a method of generating a fingerprint for a gemstone (5), for example a diamond, using x-ray imaging. The fingerprint comprises a three-dimensional map of a crystal or crystals present within the gemstone (5) including internal imperfections of the crystals and may also comprise further information about the gemstone (5).

Abstract: Disclosed is method of determining one or more unit cells of a poly-crystalline sample and indexing a set DV of 3D diffraction vectors . The method comprising obtaining a plurality of candidate first lattice plane normal vectors and a plurality of candidate second lattice plane normal vectors for a particular unknown grain; using said plurality of candidate first lattice plane normal vectors and said plurality of candidate second lattice plane normal vectors to select a plurality of subsets SSDV_n of the set DV of 3D diffraction vectors and processing said plurality of subsets SSDV_n of 3D diffraction vectors to determine a primary candidate unit cell PCUC defined by three lattice vectors; wherein the primary candidate unit cell PCUC is validated by evaluating the fit of the PCUC with the full set DV of 3D diffraction vectors.

Abstract: An X-ray diffraction method of mapping grain structures in a polycrystalline material sample, where an X-ray detector detects spots or line-shaped segments from beams diffracted from at least some of the grains. A processing device analyzes values received from the X-ray detector and identifies at least the position of the spots or line-shaped segments. The processing device discretizes an initial three-dimensional model of the polycrystalline material sample into voxels and reconstructs the grains in the model by iterative testing associating crystallographic orientations of the voxels to the detected spots or line-shaped segments.

Abstract: An X-ray diffraction method of mapping grain structures in a polycrystalline material sample, where an X-ray detector detects spots or line-shaped segments from beams diffracted from at least some of the grains. A processing device analyses values received from the X-ray detector and identifies at least the position of the spots or line-shaped segments. The processing device discretizes an initial three-dimensional model of the polycrystalline material sample into voxels and reconstructs the grains in the model by iterative testing associating crystallographic orientations of the voxels to the detected spots or line-shaped segments.