Emerald-cut diamond with length/width of 1.35 to 1.40; table of 55 to 60 percent; corner ratio of 13.5 to 14.5 percent; girdle thickness up to 3 percent; crown main angle of 28 to 45 degrees; first crown break angle of 2 to 6 degrees; second crown break angle of 2 to 6 degrees; pavilion main angle of 43 to 48 degrees; first pavilion break angle of 2 to 5 degrees; and second pavilion break angle of 2 to 5 degrees. Diamonds cut in accordance with these parameters may have light performance 0-grade domains on a grade map with wide crown and pavilion mains ranges. A method cuts the diamond according to the parameters, and may include selecting crown and pavilion main angles from the map, and cutting the diamond sufficiently close to the selected cutting parameters to obtain the light performance grade of 0.

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.

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.

Presented 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 comprises 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 comprises 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.

The invention relates to a cut gem comprising a girdle having four girdle sides and four girdle corners, a table realized by a flat facet, a crown which extends between the table and the girdle, in a first direction, and a pavilion which extends in a second direction, opposite to said first direction, between said girdle and a tip of the pavilion. The gem is noteworthy in that the crown has 24 facets, the pavilion has 32 facets and in that the four girdle sides are identical in the form of an arc of a circle, the concavity of which is oriented towards the outside of the gem.

A gemstone includes: a table defining an area; and a scanable indicia formed in the gemstone at least partially positioned within an orthographic projection of the area extending along an axis, the axis extending perpendicularly through the table.

A timepiece (1) having at least one colored transparent stone (10), and a support (20) with at least one opening (200) for receiving this colored transparent stone (10). The ratio between the height (h) and width (L) of the colored transparent stone (10) is less than 50% , and the support (20) is made from anodised titanium or anodised aluminium. Advantageously, the color of the colored transparent stone (10) in the timepiece (1) is enhanced by that of the support (20).

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.

The invention is directed to shallow pavilion, cut diamonds having excellent optical characteristics. The shallow pavilion cut diamonds of the invention have a table with a table plane and a girdle. The cut diamonds have a shape and configuration that result in a specific total depth percentage, a specific crown height percentage, a specific girdle height percentage and a specific table percentage. A crown surface is located between the table and the girdle and extends in a crown angle to the table plane. A pavilion surface extends at a pavilion angle relative to the table. The pavilion surface includes a plurality of substantially planar main pavilion facets, each of which extend from the girdle to a pointed culet defining the bottom most portion of the cut diamond. The crown angle is in the range of between about 29 degrees to about 36 degrees, and the pavilion angle is in the range of between about 15 degrees and about 34.5 degrees. The shallow pavilion, cut diamonds of the invention may be either round shaped cut diamonds or fancy shaped cut diamonds.

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.