US 4,306,427 AGranted

Chrysoberyl gemstones

AssigneeAllied Corporation

InventorStanley W. Urban

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Abstract

A chrysoberyl gemstone cut in a modified brilliant style is provided. The gemstone has seven rows of facets, including a girdle comprising rectangular facets. Each row contains eight, ten or twelve facets. The bottom row of facets is visible as a rosette pattern when the gemstone is viewed through the table.

Claims9

Dependent claims

A brilliant single crystal alexandrite gemstone having an axis of symmetry, a crown, a girdle and a pavilion,

said crown comprising:
(a) a table in the form of a first regular n-sided polygon whose plane is substantially perpendicular to the axis of symmetry,
(b) n substantially congruent triangular star facets, each facet having at least two substantially equal sides and a base coinciding with a side of the table;
(c) n substantially congruent triangular upper girdle facets, each facet having at least two substantially equal sides, a base coinciding with a side of a second regular n-sided polygon of the girdle and a common vertex with a star facet;
(d) n substantially congruent kite-shaped main facets, each facet having one side coinciding with each of four surrounding triangular facets, one vertex coinciding with a vertex of the table facet and an opposite vertex coinciding with a vertex of said second regular n-sided polygon of the girdle;
said girdle comprising:
(e) n substantially congruent rectangular facets, each facet being in a plane substantially parallel to the axis of symmetry, the upper sides of the facets forming said second regular n-sided polygon and the lower sides of the facets forming a third regular n-sided polygon, the planes of said second and third regular n-sided polygons being substantially perpendicular to the axis of symmetry;
and said pavillion comprising:
(f) n substantially congruent triangular lower girdle facets, each facet having at least two substantially equal sides and a base coinciding with a side of said third regular n-sided polygon of the girdle;
(g) n substantially congruent kite-shaped culet facets, each facet having a common vertex on the axis of symmetry and an opposite vertex coinciding with a vertex of a lower girdle facet and being substantially symmetrical about a line joining the common vertex and opposite vertex, the projection of said line on the plane of the table having length less than half the length of a line joining the centers of opposite sides of the table, whereby said culet facets present a rosette pattern when viewed through the table;
and
(h) n substantially congruent kite-shaped pavilion main facets, each facet having an upper vertex coinciding with a vertex of the third regular n-sided polygon of the girdle and a lower vertex coinciding with a vertex of a culet facet and being substantially symmetrical about a line joining the upper and lower vertexes,
where n is an even number between 7 and 13.

10 more elements

Dependencies are inferred from the claim text.

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Abstract

A brilliant single crystal alexandrite gemstone having an axis of symmetry, a crown, a girdle and a pavilion,

said crown comprising:
(a) a table in the form of a first regular n-sided polygon whose plane is substantially perpendicular to the axis of symmetry,
(b) n substantially congruent triangular star facets, each facet having at least two substantially equal sides and a base coinciding with a side of the table;
(c) n substantially congruent triangular upper girdle facets, each facet having at least two substantially equal sides, a base coinciding with a side of a second regular n-sided polygon of the girdle and a common vertex with a star facet;
(d) n substantially congruent kite-shaped main facets, each facet having one side coinciding with each of four surrounding triangular facets, one vertex coinciding with a vertex of the table facet and an opposite vertex coinciding with a vertex of said second regular n-sided polygon of the girdle;
said girdle comprising:
(e) n substantially congruent rectangular facets, each facet being in a plane substantially parallel to the axis of symmetry, the upper sides of the facets forming said second regular n-sided polygon and the lower sides of the facets forming a third regular n-sided polygon, the planes of said second and third regular n-sided polygons being substantially perpendicular to the axis of symmetry;
and said pavillion comprising:
(f) n substantially congruent triangular lower girdle facets, each facet having at least two substantially equal sides and a base coinciding with a side of said third regular n-sided polygon of the girdle;
(g) n substantially congruent kite-shaped culet facets, each facet having a common vertex on the axis of symmetry and an opposite vertex coinciding with a vertex of a lower girdle facet and being substantially symmetrical about a line joining the common vertex and opposite vertex, the projection of said line on the plane of the table having length less than half the length of a line joining the centers of opposite sides of the table, whereby said culet facets present a rosette pattern when viewed through the table;
and
(h) n substantially congruent kite-shaped pavilion main facets, each facet having an upper vertex coinciding with a vertex of the third regular n-sided polygon of the girdle and a lower vertex coinciding with a vertex of a culet facet and being substantially symmetrical about a line joining the upper and lower vertexes,
where n is an even number between 7 and 13.

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