A sparkling, oblong-shaped precious stone, such as an emerald or cushion cut diamond is formed by a planar table facet, a girdle, two pairs of long crown facets located between the table facet and the girdle, and the two pairs of long pavilion facets located between the base of the stone and the girdle.

Provided is a gemstone treated with a cut expressing a reflected image pattern not recognized before, wherein the gemstone includes the crown 100 having the table 110 and plural bezel facets 130, and the pavilion 200 having the culet 210 and plural main facets 220; the girdle 300 is formed between the crown 100 and the pavilion 200; a direction of a horizontal component of an inclination direction of the bezel facet 130 from the table 110 to the girdle 300 is set to be different from a direction of a horizontal component of an inclination direction of the main facet 220 from the culet 210 to the girdle 300; and inclination angles of the bezel facet 130 and the main facet 220 are set so that a light that enters the table 110 is reflected by two of the main facets 220 and emitted from the bezel facet 130.

Provided is a gemstone treated with a cut expressing a reflected image pattern not recognized before, wherein the gemstone includes the crown 100 having the table 110 and plural bezel facets 130, and the pavilion 200 having the culet 210 and plural main facets 220; the girdle 300 is formed between the crown 100 and the pavilion 200; a direction of a horizontal component of an inclination direction of the bezel facet 130 from the table 110 to the girdle 300 is set to be different from a direction of a horizontal component of an inclination direction of the main facet 220 from the culet 210 to the girdle 300; and inclination angles of the bezel facet 130 and the main facet 220 are set so that a light that enters the table 110 is reflected by two of the main facets 220 and emitted from the bezel facet 130.

One variation of a diamond composition includes carbon: including a first amount of carbon-13 isotopes and a second amount of carbon-12 isotopes; and sourced from a hydrocarbon mixture including hydrocarbons and formed via methanation of a carbon dioxide mixture. The carbon dioxide mixture: sourced from a sample of air including carbon dioxide and impurities; conveyed through a separation unit configured to remove impurities; including carbon dioxide and impurities; conveyed through a distillation column configured to regulate amounts of carbon-13 isotopes and carbon-12 isotopes; and exhibiting a target ratio of carbon-13 isotopes to carbon-12 isotopes at an outlet of the distillation column. The diamond composition: formed via chemical vapor deposition; and exhibiting an isotopic signature defining a final ratio of the first amount of carbon-13 isotopes to the second amount of carbon-12 isotopes within a first target range corresponding to the target ratio exhibited by the carbon dioxide mixture.

One variation of a diamond composition includes carbon: including a first amount of carbon-13 isotopes and a second amount of carbon-12 isotopes; and sourced from a hydrocarbon mixture including hydrocarbons and formed via methanation of a carbon dioxide mixture. The carbon dioxide mixture: sourced from a sample of air including carbon dioxide and impurities; conveyed through a separation unit configured to remove impurities; including carbon dioxide and impurities; conveyed through a distillation column configured to regulate amounts of carbon-13 isotopes and carbon-12 isotopes; and exhibiting a target ratio of carbon-13 isotopes to carbon-12 isotopes at an outlet of the distillation column. The diamond composition: formed via chemical vapor deposition; and exhibiting an isotopic signature defining a final ratio of the first amount of carbon-13 isotopes to the second amount of carbon-12 isotopes within a first target range corresponding to the target ratio exhibited by the carbon dioxide mixture.

The invention relates to a cemented carbide composition producing method for precious metal, which includes a titanium nitride component contained therein and shows excellent workability, corrosion resistance, reduction in weight and other desirable mechanical properties, as well as the low amount of nickel used as a metallic binder and an aluminum oxide coating helps to suppress potential negative skin reactions.

The invention relates to a cemented carbide composition producing method for precious metal, which includes a titanium nitride component contained therein and shows excellent workability, corrosion resistance, reduction in weight and other desirable mechanical properties, as well as the low amount of nickel used as a metallic binder and an aluminum oxide coating helps to suppress potential negative skin reactions.

Aspects of the invention may be directed to a method of creating a predetermined structure from a diamond bulk. In some embodiments, the method may include: irradiating the diamond bulk with at least one laser having a focal point at a predetermined location, the laser may create graphitization at locations where the focal point of the laser engages the diamond bulk; at least one of: moving the diamond bulk to be positioned with the focal point of the laser within the diamond bulk, and moving the at least one laser such that diamond bulk be positioned with the focal point of the laser, along at least one axis wherein the movement corresponds to a predefined scheme; removing of the graphite from the diamond bulk; and extracting the predetermined structure from the diamond bulk.

A gemstone includes a crown, a pavilion, and a girdle disposed between the crown and the pavilion. 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 main crown facets, upper intermediate crown facets, lower main crown facets, lower intermediate 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, lower candle facets, lower main pavilion facets, upper candle facets, upper 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.