Methods, apparatus, and systems for fabricating diffractive structures on gemstones for high optical performance are provided. In one aspect, a method includes obtaining a plurality of gemstone characteristics of a gemstone, determining that the gemstone exhibits each of the plurality of gemstone characteristics within a respective predetermined range, identifying a diffractive structure setting associated with a combination of the respective predetermined ranges for the plurality of gemstone characteristics, and fabricating diffractive structures on the gemstone according to the diffractive structure setting.

Presented herein is a diamond comprising a table, a crown, a girdle, a pavilion, and a culet. The table is rectangular, having a length and a width. The table includes a first side, adjacent to a second side, adjacent to a third side, and adjacent to a fourth side. The first side of the table is directly connected with a first facet of the girdle. The second side of the table is directly connected with a second facet of the girdle. The crown includes a plurality of facets connecting the third side and the fourth side of the table to the girdle. The pavilion is connected to the girdle. The culet is positioned directly below a point having a 1% deviation from the center of the girdle.

A gemstone is configured to yield a hearts and arrows pattern when subjected to light. The gemstone has a length, a width and a height. The gemstone includes a crown portion, a girdle and a pavilion portion. The crown portion has a height of about 10-14.5% of the length of the gemstone and has four sides and four corners where the four corners connect the four sides to each other. The crown portion includes an octagonal table facet, 8 star facets of equal geometry and dimension positioned around the octagonal table facet so as to enclose the octagonal table facet, and other facets. The girdle has a variable thickness extending circumferentially along the gemstone. The pavilion portion has a height of about 45.5-54% of the length of the gemstone and includes 8 main pavilion facets, 16 pavilion half facets positioned around the main pavilion facets, and other facets.

Incident light enters a faceted gemstone and is routed along optical paths to exit the gemstone as emergent light. At least one diffraction grating is patterned on the gemstone in an asymmetrical manner relative to an axis of symmetry. The diffraction grating has a diffractive structure positioned on at least one facet for diffracting the light being routed along at least one of the optical paths to enhance color dispersion of the emergent light. The diffraction grating is the only diffraction grating to diffract the light being routed along the at least one optical path to diminish haze of the emergent light.

Methods, systems, and media for rating and analyzing diamonds are provided. In some embodiments, the method comprises: receiving, from a user device, a selection of a diamond from a plurality of diamonds; in response to receiving the selection of the diamond, receiving at least one image of the diamond and a plurality of ratings corresponding to the diamond; calculating an eye-cleanliness score corresponding to the diamond that indicates a clarity of the diamond when viewed without magnification and a brilliance score corresponding to the diamond that indicates an amount of light reflected through the diamond based on the at least one image of the diamond and at least one rating of the plurality of ratings corresponding to the diamond; and causing a user interface to be presented on the user device indicates the eye-cleanliness score and the brilliance score.

The invention discloses a symmetrically cut gemstone of princess cut (FIG. 1) or cushion cut (FIG. 8) which visually encompassing a heart shape (Z1) within and its method of manufacture. The gemstone has a lower pavilion with a plurality of pavilion facets which emerge upwardly from the culet and are arranged around the pavilion surface on either side of a axis line (C) (FIG. 3, 10). The pavilion facets are symmetrical to the corresponding pavilion facets across the axis. The pavilion facets comprise of triangoid facets (L), chevron facets (M,N) and pavilion main facets, all at specific angles in relation to each other. The pavilion main facet (O) is kite shaped, with short sides (P) converging at the culet, long sides (Q) at 1.sup.st points (R) at a girdle depth of 70 to 86% and the long and short sides at 2.sup.nd points (S) at a girdle depth of 88% to 95%; Pairs of pavilion short half facets (T) are faceted from chevron facets (M,N), and alternate the sides of the pavilion main facets (O) and are formed along a cable (RR) joining the 1.sup.st points. The gemstone is angled at 1st pavilion short half angles (Y) at the girdle depth of 1st point, and are 15 to 30 less than the Triangle main angle (W), and 2 to 9 less than the chevron angles (X,X1). The 1st pavilion short half angles (Y) along the cable of alternate pairs of chevron facets have a variance of 0.05 to 9; (FIG. 5,5a, 11, 11a). The 1.sup.st common interphase of the pavilion short half facets intersects (R) the cable; 2.sup.nd pavilion short lower half angles (Z) around the gemstone at the girdle depth of the 2.sup.nd point, are 0.25 to 8 less than 1.sup.st pavilion short half angles (Y); The angular variance along 2.sup.nd common interphase between pavilion main facets (O) and the adjacent pavilion short half facets (T), is 0.05 to 9, and at the short side interphase of adjacent pavilion main

Embodiments of the disclosure provide a gemstone, jewelry piece, and method for faceting a gemstone. The gemstone, includes: a top portion having a spheroidal surface, the spheroidal surface acting as a refractive surface for light incident on the top portion of the gemstone and focal point lens originator; and a bottom portion shaped as a cone, the cone acting as a light axis to form a focal point on a reflective surface at a base of the gemstone.

A gemstone includes a crown, a pavilion, and a girdle disposed between the crown and the pavilion. The girdle has a pear-shaped cross-section with a rounded end a tapered end narrower than the rounded end. The surface of the gemstone is generally divided into a number of groups of interlocking facets disposed at a variety of angles. The groups of facets comprising the surface of the crown generally include star facets, upper intermediate crown facets, lower intermediate crown facets, main crown facets, and upper girdle facets. The upper girdle facets generally abut an upper edge of the girdle. The groups of facets comprising the surface of the pavilion include culet-adjacent facets, candle facets, main pavilion facets, and lower girdle facets. The lower girdle facets generally abut a lower edge of the girdle.

A gemstone includes a crown, a pavilion, and a girdle disposed between the crown and the pavilion. The girdle has an octagon-shaped cross-section. The surface of the gemstone is generally divided into a number of groups of interlocking facets disposed at a variety of angles. The groups of facets comprising the surface of the crown generally include star facets, upper intermediate crown facets, lower intermediate crown facets, main crown facets, and upper girdle facets. The upper girdle facets generally abut an upper edge of the girdle. The groups of facets comprising the surface of the pavilion include culet-adjacent facets, candle facets, main pavilion facets, and lower girdle facets. The lower girdle facets generally abut a lower edge of the girdle.

A gemstone includes a crown, a pavilion, and a girdle disposed between the crown and the pavilion. The girdle has an elliptical cross-section with a major axis and a minor axis. The surface of the gemstone is generally divided into a number of groups of interlocking facets disposed at a variety of angles. The groups of facets comprising the surface of the crown generally include star facets, upper intermediate crown facets, lower intermediate crown facets, main crown facets, and upper girdle facets. The upper girdle facets generally abut an upper edge of the girdle. The groups of facets comprising the surface of the pavilion include culet-adjacent facets, candle facets, main pavilion facets, and lower girdle facets. The lower girdle facets generally abut a lower edge of the girdle.