Abstract: The invention relates to a gemstone cut, comprising a crown having a flat table and main crown facets (10-12) being arranged around the table (1) and being inclined relative to the table, a girdle (5) at which the gemstone has its largest transverse dimension, and a pavilion adjoining the girdle from below the girdle and having main pavilion facets (7) around the girdle, whereby the number of the main pavilion facets is odd. The invention also relates to an article comprising a gemstone according to the invention and a method for improving the optical properties of a gemstone.

Abstract: A decorative structure (20) comprising a planar support (22) and a faceted microstructure (24) on at least one side of the planar support (22) is provided. The decorative structure (20) may further comprise an at least partially reflective layer (26) configured to at least partially reflect light that passes through the microstructure (24). The faceted microstructure (24) comprises a plurality of grooves (28) creating a pattern of facets (30) over the surface of the support (22), such that the microstructure (24) is capable of splitting incident light into spectral colours. In embodiments, the grooves (28) have a triangular or V-shaped profile. Methods of making a decorative structure(20) and articles incorporating the decorative structure (20) are also described.

Abstract: The invention relates to a gemstone cut, comprising a crown having a flat table and main crown facets (10-12) being arranged around the table (1) and being inclined relative to the table, a girdle (5) at which the gemstone has its largest transverse dimension, and a pavilion adjoining the girdle from below the girdle and having main pavilion facets (7) around the girdle, whereby the number of the main pavilion facets is odd. The invention also relates to an article comprising a gemstone according to the invention and a method for improving the optical properties of a gemstone.

Abstract: The invention relates to a gemstone cut, comprising a crown having a flat table and main crown facets (10-12) being arranged around the table (1) and being inclined relative to the table, a girdle (5) at which the gemstone has its largest transverse dimension, and a pavilion adjoining the girdle from below the girdle and having main pavilion facets (7) around the girdle, whereby the number of the main pavilion facets is odd. The invention also relates to an article comprising a gemstone according to the invention and a method for improving the optical properties of a gemstone.

Abstract: A gemstone with a chaton cut has tapering facets of a crown adjoin a flat table all the way round inclined relative to the table. The facets extend as far as a rondist at which the gemstone has the largest transverse dimension. A pavilion of facets, preferably terminating at a point, adjoins below the rondist. The gemstone is at least partially made of glass, and the crown angle (?) is between 40.5° and 42.5°.

Abstract: A gemstone has a chaton cut, in which a crown adjoins a flat table and has facets that are inclined downwardly relative to the table all the way round, wherein the crown has main facets that extend substantially from the table as far as a girdle at which the gemstone has the largest transverse dimension. A pavilion of facets, preferably facets converging to a point, adjoins below the girdle. The gemstone consists preferably entirely of topaz, and the angle of the main facets relative to a cross-sectional face arranged parallel to the table is between 32.5° and 34.5°.

Abstract: The invention relates to a gemstone (1) having a chaton cut, in which a crown (2) adjoins a flat table (5) and has facets (11, 12, 13) that are inclined downwardly relative to the table (5) all the way round, wherein the crown (2) has main facets (11) that extend substantially from the table (5) as far as a girdle (4) at which the gemstone (1) has the largest transverse dimension, and wherein a pavilion (3) of facets (8, 9, 10), preferably facets converging to a point, adjoins below the girdle (4), and wherein the gemstone (1) consists preferably entirely of topaz, wherein the angle of the main facets (11) relative to a cross-sectional face (7) arranged parallel to the table (5) is between 32.5° and 34.5°.

Abstract: Gemstone with a chaton cut, in which tapering facets of a crown adjoin a flat table all the way round inclined relative to the table, the said facets extending as far as a rondist at which the gemstone has the largest transverse dimension, wherein a pavilion of facets preferably terminating at a point adjoins below the rondist, and wherein the gemstone is at least partially made of glass, and wherein the crown angle (?) is between 40.5° and 42.5°.

Abstract: Brilliant-cut gemstone, wherein the crown angle (?) is between 32.8° and 33.0°.