U.S. patent application number 10/492712 was filed with the patent office on 2005-06-02 for rounded rectangular gemstone.
Invention is credited to Kedem, Michael, Mutai, Eran.
Application Number | 20050115275 10/492712 |
Document ID | / |
Family ID | 11075837 |
Filed Date | 2005-06-02 |
United States Patent
Application |
20050115275 |
Kind Code |
A1 |
Kedem, Michael ; et
al. |
June 2, 2005 |
Rounded rectangular gemstone
Abstract
A rounded rectangular gemstone which comprises a crown provided
with a planar table, a pavilion whose facets converge at a cutlet
being disposed below said crown, and a girdle extending from said
crown to said pavilion, said girdle being substantially
perpendicular to said table and assuming a rectangular shape when
viewed thereabove and therebelow, wherein said crown and said
pavilion have substantially circular cross-sections along a plane
parallel to said table and the facets of said pavilion are arranged
in rotational symmetry about said cutlet and in mirror symmetry
about lines of symmetry passing through said cutlet and the
midpoint of each side of said girdle and through said cutlet and
each corner of said girdle.
Inventors: |
Kedem, Michael; (Petah
Tiqwa, IL) ; Mutai, Eran; (Yavne, IL) |
Correspondence
Address: |
Kevin D McCarthy
Roach Brown McCarthy & Gruber
1620 Liberty Building
Buffalo
NY
14202
US
|
Family ID: |
11075837 |
Appl. No.: |
10/492712 |
Filed: |
January 7, 2005 |
PCT Filed: |
October 16, 2002 |
PCT NO: |
PCT/IL02/00832 |
Current U.S.
Class: |
63/32 |
Current CPC
Class: |
A44C 17/001
20130101 |
Class at
Publication: |
063/032 |
International
Class: |
A44C 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 19, 2001 |
IL |
146079 |
Claims
1. A rounded rectangular gemstone comprising a crown provided with
a planar table, a pavilion whose facets converge at a cutlet being
disposed below said crown, and a girdle extending from said crown
to said pavilion, said girdle being substantially perpendicular to
said table and assuming a rectangular shape when viewed thereabove
and therebelow, wherein said crown and said pavilion have
substantially circular cross-sections along a plane parallel to
said table and the facets of said pavilion are arranged in
rotational symmetry about said cutlet and in mirror symmetry about
lines of symmetry passing through said cutlet and the midpoint of
each side of said girdle and through said cutlet and each corner of
said girdle.
2. The gemstone of claim 1, wherein the pavilion comprises: a) a
plurality of pavilion facets the lower edge of each converging at
the cutlet, said plurality of pavilion facets comprising
kite-shaped pavilion facets and shortened pavilion facets, the
vertex of each of said kite-shaped pavilion facets extending from
the corresponding corner of the girdle, whereby each of said
kite-shaped pavilion facets is interspersed between a pair of said
shortened pavilion facets and each of said shortened pavilion
facets is interspersed between a pair of said kite-shaped pavilion
facets, said kite-shaped and shortened pavilion facets arranged in
rotational symmetry about said cutlet; b) a plurality of lower
hexagon facets arranged in such a way that a pair of lower hexagon
facets is disposed between each pair of adjacent pavilion facets,
each of said pair of lower hexagon facets comprising a larger and
smaller facet, whereby said plurality of lower hexagon facets is
provided with mirror symmetry about lines of symmetry passing
through said cutlet and the midpoint of each side of the girdle and
through said cutlet and each corner of the girdle; and c) a
plurality of hexagon facets, one side being collinear with the
girdle, four sides being collinear with corresponding lower hexagon
facets, and the remaining side being collinear with the end of said
shortened pavilion facet.
3. The gemstone of claim 2, wherein each of the hexagon pavilions
is cut an angle ranging from 52-60 degrees, each of the lower
hexagon facets is cut an angle ranging from 47-53 degrees, and each
of the pavilion facets is cut an angle ranging from 39-44 degrees,
with respect to the table.
4. The gemstone of claim 3, wherein each of the hexagon pavilions
is cut an angle of 55 degrees, each of the lower hexagon facets is
cut an angle of 50 degrees, and each of the pavilion facets is cut
an angle of 41 degrees, with respect to the table.
5. The gemstone of claim 2, wherein the maximum depth of each
hexagon facet ranges from 25-30 percent of the maximum girdle
length and the minimum depth of each hexagon facet is 0
percent.
6. The gemstone of claim 5, wherein the maximum depth of each
hexagon facet is 27 percent of the maximum girdle length.
7. The gemstone of claim 2, wherein the pavilion depth ranges from
72-83 percent of the maximum girdle length.
8. The gemstone of claim 7, wherein the pavilion depth ranges from
77-78 percent of the maximum girdle length.
9. The gemstone of claim 2, wherein 8 pavilion facets are employed,
16 lower hexagon facets are employed and 4 hexagon facets are
employed.
10. The gemstone of claim 2, wherein the crown comprises: a) a
plurality of triangular star facets, the long side of which is
collinear with one side of the table; b) a plurality of
intermediate bezel facets, two sides of each of said intermediate
bezel facets being collinear with the short side of two adjacent
star facets and the remaining two sides converging to the midpoint
of one side of the girdle; c) a plurality of corner bezel facets,
two short sides of each of said corner bezel facets being collinear
with the short side of two adjacent star facets and the long sides
converging to the corresponding corner of the girdle; and d) a
plurality of triangular upper girdle facets, the long side of each
of said upper girdle facets being collinear with the girdle and one
of the short sides being collinear with a short side of an adjacent
upper girdle facets.
11. The gemstone of claim 10, wherein each star facet is cut at
angle ranging from 13-22 degrees, each intermediate and corner
bezel facet is cut at an angle ranging from 27-40 degrees, and each
upper girdle facet is cut at an angle ranging from 39-62 degrees,
with respect to the table.
12. The gemstone of claim 11, wherein each star facet is cut at an
angle ranging from 15.0-19.5 degrees, each intermediate and corner
bezel facet is cut at an angle ranging from 33.0-35.0 degrees and
each upper girdle facet is cut at an angle ranging from 47-55
degrees with respect to the table.
13. The gemstone of claim 10, wherein the vertex of each corner
bezel facet that abuts each corresponding girdle corner defines a
circle whose center is the projection of the cutlet onto the table,
thereby providing radial symmetry.
14. The gemstone of claim 10, wherein the vertex of each
intermediate bezel facet that abuts the midpoint of the
corresponding girdle side defines a circle whose center is the
projection of the cutlet onto the table, thereby providing radial
symmetry.
15. The gemstone of claim 10, wherein 8 star facets, 4 intermediate
bezel facets, 4 corner bezel facets and 16 upper girdle facets are
employed.
16. The gemstone of claim 10, wherein each hexagon facet is not
projected onto a corner bezel facet.
17. The gemstone of claim 1, wherein the girdle has a non-uniform
height, the minimum height thereof ranging from 1-5 percent of the
maximum girdle length and the maximum height thereof ranging from
10-20 percent of the maximum girdle length.
18. The gemstone of claim 1, wherein each side of the girdle ranges
from 86-94 degrees, with respect to the table.
19. The gemstone of claim 1, wherein the ratio of maximum girdle
length to minimum girdle length, when measured on a plane parallel
to the table, ranges from 1-5.
20. The gemstone of claim 1, wherein the table size ranges from
53-63 percent, and preferably at 58 percent, of the maximum girdle
length.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of gemstones.
More particularly, the invention relates to a rounded rectangular
gemstone exhibiting the brilliance and fire of a Brilliant cut
gemstone.
BACKGROUND OF THE INVENTION
[0002] Two commonly found crystalline structures of diamonds are
the octahedron and dodecahedron. A diamond with an octahedral
structure has eight triangular facets, or sides, such that each
facet is equally spaced from the center. A diamond with a
dodecahedral structure has twelve rhombic facets, such that each
facet intersects two axes of symmetry, forming an equal spacing
from the point of intersection, and perpendicular to a third axis
of symmetry.
[0003] To properly utilize these crystalline structures and to
minimize loss of material during diamond cutting (normally referred
to as polishing), two corresponding diamond cuts are commonly used:
the Round-Brilliant Cut and the Princess cut. The Round Brilliant
Cut is the most popular cut, achieving a good balance of brilliance
and dispersion as a result of its symmetrical shape, and is
generally produced from a dodecahedron, which approaches a
spherical shape; however a material loss of 40-50 percent results
with this cut. Traditionally a Round Brilliant Cut is produced with
58 facets. A Princess cut, having a rectangular shape and resulting
in a corresponding material loss of approximately 20 percent, is
generally produced from a given octahedral rough diamond, while the
Round Brilliant Cut is generally produced from a given dodecahedral
rough diamond. Even though a Princess cut diamond has a much lower
material loss than that of a Brilliant cut, the cost of a Princess
cut diamond is not significantly lower since it is produced from an
octahedral rough diamond. The cost of an octahedral rough diamond
is much higher than of a dodecahedron, from which a Brilliant cut
is produced.
[0004] Two important characteristics of a diamond when used as a
gem are its brilliance and fire. External brilliance, or luster,
refers to the amount of light that is reflected from the top of the
diamond. Internal brilliance is determined by the light rays that
enter the top (generally referred to as "crown"), and that are
reflected from facets of the base (generally referred to as
"pavilion") and then are reflected again through the top (or
through the so-called "table", if provided) as undispersed light.
Fire, also referred to as dispersion, occurs when white light is
separated into its spectral colors so that the gem sparkles when
properly cut.
[0005] Maximum brilliance occurs when a diamond is cut to enable
maximum light return through the surface of the diamond. As shown
in FIG. 1, light rays 2 penetrate top 3 of the diamond, are
reflected from lower facets 4 and return to top 3. Even if a light
ray 2 penetrates a top facet 5, it will be reflected through top 3
and will be visible to an observer as undispersed light. If the
diamond cut significantly deviates from the optimal dimensions and
shapes, light may escape from the side or bottom of the gem, and as
a result diminishing its luster. The Gemological Institute of
America (GIA) defines Class 1 stones, which are provided with a
harmonious balance between their physical dimensions and optical
display, as having table sizes from 53 to 60 percent, crown angles
from 34.degree. to 35.degree., even girdles that are medium to
slightly thick, pavilion depths very close to 43 percent, small to
medium cutlets, and very good to excellent polish and symmetry. The
physical characteristics of a diamond will be defined
hereinafter.
[0006] Diamond appraisers rely on another attribute, in addition to
those mentioned above, in order to determine the quality of the
cut. Since the cross section of both the top and bottom portions of
a Brilliant Cut diamond is round, the image of the table is
reflected around the cutlet, within the bottom portion of the
diamond. The table reflection is an indication of the depth of the
pavilion. For example, at a pavilion depth of 48 percent, a black
spot appears throughout the table, whereas at the ideal pavilion
depth of 43 percent the table reflection appears as a spot
encompassing one-third of the area of the table. It would be
appreciated that the appearance of the table reflection occurs only
with Brilliant Cut diamonds due to its radial symmetry.
[0007] There have been attempts to reproduce the dispersion and
brilliant of Brilliance Cut diamonds without a corresponding high
material loss. U.S. Pat. Nos. 4,020,649 and 4,555,916 to Grossbard
disclose a step-cut diamond, usually referred to as an Emerald cut,
whose facets are broad with flat planes resembling a flight of
stairs, that exhibits improved brilliance. According to these
patents a diamond is cut with a straight edged polygonal girdle, a
crown having table and girdle breaks in addition to a table, a
pyramidal base having girdle and cutlet breaks, and a cutlet. U.S.
Pat. No. 5,970,744 to Greeff discloses a cut cornered mixed-cut
square gemstone in which the crown and pavilion are substantially
square with four equal sides and corners about one-third the length
of the sides. The pavilion sides and corners are defined by eight
rib lines which extend substantially continuously from the girdle
to the cutlet. Although these patents attempt to achieve the good
brilliance and dispersion of a Brilliant cut, the effect
nevertheless does not duplicate that of the Brilliant cut.
Furthermore, the prior art diamonds do not have radial symmetry,
and therefore a table reflection does not appear.
[0008] All of the prior art described above have not yet provided
satisfactory solutions to the problem of producing a diamond with
the brilliance and dispersion of a Brilliant cut without a
corresponding high material loss.
[0009] It is an object of the present invention to provide a
diamond exhibiting the brilliance and dispersion of a Brilliant
cut.
[0010] It is an additional object of the present invention to
provide a diamond lacking the large material loss of a Brilliant
cut.
[0011] It is an additional object of the present invention to
provide a diamond in which a table reflection appears.
[0012] It is yet an additional object of the present invention to
provide a cost-effective diamond that is produced from a
dodecahedral rough diamond
[0013] Other objects and advantages of the invention will become
apparent as the description proceeds.
SUMMARY OF THE INVENTION
[0014] The present invention relates to a rounded rectangular
gemstone comprising a crown provided with a planar table, a
pavilion whose facets converge at a cutlet being disposed below
said crown, and a girdle extending from said crown to said
pavilion, said girdle being substantially perpendicular to said
table and assuming a rectangular shape when viewed thereabove and
therebelow, wherein said crown and said pavilion have substantially
circular cross-sections along a plane parallel to said table and
the facets of said pavilion are arranged in rotational symmetry
about said cutlet and in mirror symmetry about lines of symmetry
passing through said cutlet and the midpoint of each side of said
girdle and through said cutlet and each corner of said girdle.
[0015] The pavilion comprises:
[0016] a) a plurality of pavilion facets the lower edge of each
converging at the cutlet, said plurality of pavilion facets
comprising kite-shaped pavilion facets and shortened pavilion
facets, the vertex of each of said kite-shaped pavilion facets
extending from the corresponding corner of the girdle, whereby each
of said kite-shaped pavilion facets is interspersed between a pair
of said shortened pavilion facets and each of said shortened
pavilion facets is interspersed between a pair of said kite-shaped
pavilion facets, said kite-shaped and shortened pavilion facets
arranged in rotational symmetry about said cutlet;
[0017] b) a plurality of lower hexagon facets arranged in such a
way that a pair of lower hexagon facets is disposed between each
pair of adjacent pavilion facets, each of said pair of lower
hexagon facets comprising a larger and smaller facet, whereby said
plurality of lower hexagon facets is provided with mirror symmetry
about lines of symmetry passing through said cutlet and the
midpoint of each side of the girdle and through said cutlet and
each corner of the girdle; and
[0018] c) a plurality of hexagon facets, one side being collinear
with the girdle, four sides being collinear with corresponding
lower hexagon facets, and the remaining side being collinear with
the end of said shortened pavilion facet.
[0019] The hexagon pavilions are cut at an angle ranging from 52-60
degrees, each of the lower hexagon facets is cut at an angle
ranging from 47-53 degrees, and each of the pavilion facets is cut
at an angle ranging from 39-44 degrees, with respect to the
table.
[0020] Preferably, each of the hexagon pavilions is cut at an angle
of 55 degrees, each of the lower hexagon facets is cut at an angle
of 50 degrees, and each of the pavilion facets is cut at an angle
of 41 degrees, with respect to the table.
[0021] The maximum depth of each hexagon facet ranges from 25-30
percent, and preferably 27 percent, of the maximum girdle length
and the minimum depth of each hexagon facet is 0 percent.
[0022] As referred to herein, unless otherwise stated, the term
"percent" relates to the ratio of a given gemstone dimension to the
maximum girdle length. The girdle length is measured along a plane
parallel to the table.
[0023] The pavilion depth ranges from 72-83 percent, and preferably
from 77-78 percent, of the maximum girdle length.
[0024] Preferably 8 pavilion facets are employed, 16 lower hexagon
facets are employed and 4 hexagon facets are employed.
[0025] The crown comprises:
[0026] a) a plurality of triangular star facets, the long side of
which is collinear with one side of the table;
[0027] b) a plurality of intermediate bezel facets, two sides of
each of said intermediate bezel facets being collinear with the
short side of two adjacent star facets and the remaining two sides
converging to the midpoint of one side of the girdle;
[0028] c) a plurality of corner bezel facets, two short sides of
each of said corner bezel facets being collinear with the short
side of two adjacent star facets and the long sides converging to
the corresponding corner of the girdle; and
[0029] d) a plurality of triangular upper girdle facets, the long
side of each of said upper girdle facets being collinear with the
girdle and one of the short sides being collinear with a short side
of an adjacent upper girdle facets.
[0030] Each star facet is cut at angle ranging from 13-22 degrees,
each intermediate and corner bezel facet is cut at an angle ranging
from 27-40 degrees, and each upper girdle facet is cut at an angle
ranging from 39-62 degrees, with respect to the table.
[0031] Preferably, each star facet is cut at an angle ranging from
15.0-19.5 degrees, each intermediate and corner bezel facet is cut
at an angle ranging from 33.0-35.0 degrees and each upper girdle
facet is cut at an angle ranging from 47-55 degrees with respect to
the table.
[0032] The vertex of each corner bezel facet that abuts each
corresponding girdle corner defines a circle whose center is the
projection of the cutlet onto the table, thereby providing radial
symmetry.
[0033] The vertex of each intermediate bezel facet that abuts the
midpoint of the corresponding girdle side defines a circle whose
center is the projection of the cutlet onto the table, thereby
providing radial symmetry.
[0034] The structure of the gemstone according to the present
invention, wherein each hexagon facet is not projected onto a
corner bezel facet, precludes the appearance of any shadows.
[0035] The girdle has a non-uniform height. The minimum height of
the girdle ranges from 1-5 percent and the maximum height of the
girdle ranges from 10-20 percent. Each side of the girdle ranges
from 86-94 degrees, and is preferably 90 degrees, with respect to
the table.
[0036] The table size ranges from 53-63 percent, and preferably at
58 percent, of the maximum girdle length.
[0037] Preferably 8 star facets, 4 intermediate bezel facets, 4
corner bezel facets and 16 upper girdle facets are employed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] In the drawings:
[0039] FIG. 1 illustrates the reflection of light rays within a
diamond;
[0040] FIG. 2 illustrates a side view of a typical Brilliant cut
diamond;
[0041] FIG. 3 illustrates the top view of a typical Brilliant cut
diamond;
[0042] FIG. 4 illustrates a bottom view of a typical Brilliant cut
diamond;
[0043] FIG. 5 illustrates a top view of a typical Princess cut
diamond;
[0044] FIG. 6 illustrates a bottom view of a typical Princess cut
diamond;
[0045] FIG. 7 illustrates a top view of a diamond according to the
present invention;
[0046] FIG. 8 illustrates a bottom view of a diamond according to
the present invention;
[0047] FIG. 9 illustrates a bottom view of a diamond according to
the present invention showing its rotational symmetry,
[0048] FIG. 10 illustrates a superimposition of the crown and
pavilion;
[0049] FIG. 11 illustrates a side view of a diamond according to
the present invention;
[0050] FIG. 12 illustrates another side view of a diamond; showing
the interconnection of the sides of the girdle;
[0051] FIG. 13 illustrates a cross-section cut along plane A-A of
FIG. 12;
[0052] FIG. 14 illustrates a cross-section cut along plane B-B of
FIG. 12;
[0053] FIG. 15 is a picture of the pavilion of a rounded
rectangular gemstone that was produced in accordance with the
present invention;
[0054] FIG. 16 is a picture of the crown of a rounded rectangular
diamond that was produced in accordance with the present
invention;
[0055] FIG. 17 is a perspective view of the gemstone of the present
invention facing a girdle corner, and
[0056] FIG. 18 is a perspective view of the gemstone of the present
invention taken above the crown.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0057] FIGS. 2-4 illustrate the shape of a typical diamond 10
produced with a Brilliant cut. As shown in a side view of diamond
10 in FIG. 2, girdle 8, a band which defines the widest part of the
diamond, divides diamond 10 into an upper portion, referred to as
the crown designated by 12, and into a lower portion, referred to
as the pavilion designated by 14. Crown 12 includes several facets
located below a horizontally disposed area 15 called the table. The
crown permits light to enter the diamond, and the pavilion allows
the light to be reflected within the gem and then returned through
the table or crown, depending on the penetration angle of the light
rays. The facets of pavilion 14 converge at cutlet 16, the smallest
facet located at the bottom of the diamond.
[0058] Before commencement of diamond polishing, in order to
achieve the cut illustrated in FIG. 2, a dodecahedron is sawed at
its midsection, thereby resulting in two rough diamonds. After
smoothening each flat portion that results, a table is produced. A
top view of crown 12 is shown in FIG. 3 in which eight star facets
21(a)-(h) are inclined with respect to table 15. Each star facet 21
is triangular and equally sized, and the long side of which is
collinear with one end of octagonal table 15. Crown 12 is also
provided with eight equally sized bezel facets 24(a)-(h). Each
bezel facet 24 is quadralarly shaped, such that two of its sides
are collinear with two short sides of adjacent star facets 21. One
of the vertices abuts a corresponding vertex of an adjacent bezel
facet, and the lower vertex of each bezel facet 24 abuts girdle
8.
[0059] As seen more clearly in FIGS. 3 and 4, girdle 8 is circular.
After preparation of table 15, the girdle, which is perpendicular
with respect to the table, is cut with a cutting machine such that
the circularity thereof is provided with an accuracy of 20 microns.
After cutting of girdle 8, bezel facets 24 and then sixteen upper
girdle facets 31-38 are produced, followed by the polishing of star
facets 21. Bezel facets, star facets and upper girdle facets are
cut by means of a polishing mill. During polishing eight sets of
triangularly shaped upper girdle facets 31(a),(b)-38(a),(b) are
produced, such that the two facets of each set have collinear sides
and a vertex of one set abuts a corresponding vertex of an adjacent
set. The second side of an upper girdle facet abuts girdle 8, while
the third side coincides with a bezel facet.
[0060] The facets of crown 12, as well as those of pavilion 14, as
will be described hereinafter, are cut in such a way so as to
provide a round shape that has rotational symmetry with respect to
cutlet 16, thereby enabling the appearance of table reflection 17.
The cut of the crown results in a particular table size, defined as
the ratio of the length T of table 15 to the length G of girdle 8,
and in a particular crown angle .o slashed. (see FIG. 2), defined
as the angle of bezel facets 24 with respect to girdle 8.
[0061] A bottom view of pavilion 14 is shown in FIG. 4. Pavilion 14
is comprised of eight pairs of lower girdle facets 40, which are
triangularly shaped, eight kite-shaped pavilion facets 41 and
cutlet 16. The lower girdle facets are cut after the polishing of
the pavilion facets. The two lower girdle facets 40 of each pair
have collinear sides. The upper vertex of each pavilion facet 41
abuts girdle 8 and separates each pair of lower girdle facets.
Lower girdle facets 40 and pavilion facets 41 are cut in such a way
so as to provide pavilion 14 with a tapered and conical appearance,
with the facets converging at cutlet 16. The cut of the pavilion
results in a particular pavilion depth, defined as the ratio of the
depth of pavilion 14, when measured in a plane perpendicular to
table 15 (FIG. 3), to the length of girdle 8.
[0062] FIGS. 5 and 6 illustrate top and bottom views, respectively,
of a Princess cut diamond. Girdle 45 is square, on top of which is
cut crown 43, comprised of a plurality of steps, bezel facets, star
facets and a table. Pavilion 47 is comprised of lower girdle facets
and pavilion facets. It would be appreciated that the various
facets are arranged in sets of four, and the particular
configuration of the facets is selected to minimize material loss
of the diamond during polishing.
[0063] FIG. 7 is a top view of the diamond of the present
invention, which is a rounded rectangular gemstone. The present
invention is produced from a dodecahedral rough diamond, and a
cost-effective diamond with rotational symmetry may be therefore
achieved. It would be appreciated that any gemstone may be cut with
the use of the present invention whereby the brilliance of a
Brilliant cut gemstone is noticeable; however, for sake of
illustration the ensuing description will refer to a diamond, since
a diamond cut with the use of the present invention advantageously
provides the fire of a round diamond as well as its brilliance.
[0064] Crown 50 is comprised by girdle 52, table 55, eight star
facets 21(a)-(h), eight bezel facets 56(a)-(d) and 58(a)-(d), and
sixteen upper girdle facets 60(a),(b)-67(a),(b). Girdle 52, which
assumes a rectangular shape when viewed above and below the
diamond, and defines the boundary of crown 50, is perpendicularly
disposed with respect to table 55. The table size, or ratio of
table length T to maximum girdle length G (see FIG. 11) ranges from
53-63 percent, and preferably at 58 percent. The ratio of maximum
girdle length G to its minimum length ranges from 1-5, and
preferably assumes the shape of a square, having a ratio of 1. Star
facets 21(a)-(h) are identical to those of a Brilliant cut, and the
long side of each equally sized triangular star facet is collinear
with one side of the octagonal table 55. Each star facet is cut at
angle ranging from 13-22 degrees, and preferably from 15.0-19.5
degrees, with respect to table 55. Bezel facets 58(a)-(d) have
similar proportions to those of a Brilliant cut, and two sides of
each bezel facet 58 are collinear with the short side of two
adjacent star facets 21, while the remaining two sides converge to
the midpoint of one of the projections of girdle 52.
[0065] Corner bezel facets 56(a)-(d) are adapted to the
configuration of a rectangular girdle on one hand and the
requirement of radial symmetry on the other. As a result the two
short sides of each bezel facet 56 are collinear with the short
side of two adjacent star facets 21, while the long sides converge
to a corresponding corner of girdle 52. The four vertices of the
corresponding bezel facets 56 that abut each corner of the girdle
define a circle whose center is the projection of cutlet 69 (FIG.
8) onto table 55, thereby providing radial symmetry. Similarly
radial symmetry is provided by the four vertices of intermediate
bezel facets 58 that abut the midpoint of each side of girdle 52,
by which a circle whose center is the projection of cutlet 69 onto
table 55 is traceable. Each bezel facet 56 and 58 is cut at an
angle ranging from 27-40 degrees, and preferably from 33.0-35.0
degrees, with respect to table 55. Eight sets of triangular upper
girdle facets 60(a),(b)-67(a),(b) are provided to extend from
girdle 52 to a corresponding bezel facet, whereby the two facets of
each set are disproportionate to each other. Two sets are disposed
along each side of the girdle, such that each of these two sets is
a mirror image of the other. For example, upper girdle facet 60(a)
is a mirror image of 61(b), while facet 60(b) is a mirror image of
61(a). The long side of each upper girdle facet is collinear with
girdle 52, and one of the short sides is collinear with a short
side of the other facet of the corresponding set of upper girdle
facets. The remaining side is collinear with a corresponding side
of a bezel facet 56 or 58. Each upper girdle facet is cut at an
angle ranging from 39-62 degrees, and preferably from 47-55
degrees, with respect to table 55.
[0066] FIG. 8 is a bottom view of the pavilion, generally
designated as 70. Whereas the crown of the present invention is an
adaptation of the crown of a conventional Brilliant cut diamond,
having similar types of facets although the proportions and
inclination of which are different in order to conform with the
rectangular girdle, pavilion 70 incorporates a novel type of facet
cut with six unequal sides, hereinafter referred to as a "hexagon
facet." Pavilion 70 consists of four similarly shaped hexagon
facets 72, eight sets of lower hexagon facets 76(a),(b)-83(a),(b),
eight pavilion facets 90-97 and cutlet 69.
[0067] Two types of pavilion facets are provided: kite-shaped
pavilion facets 90, 92, 94, 96 and shortened pavilion facets 91,
93, 95 97. Each pavilion facet is cut at angle ranging from 39-44
degrees, and preferably at an angle of 41 degrees, with respect to
table 55 (FIG. 7). Each pavilion facet is cut from two short sides
87 of equal length. Each kite-shaped pavilion facet is cut from two
long sides 88 of equal length, and each shortened pavilion facet is
cut from two long sides 89 of equal length. Each kite-shaped
pavilion facet is interspersed between two shortened pavilion
facets, and each shortened pavilion facets is interspersed two
kite-shaped pavilion facets, such that each short side 87 of one
pavilion facet is collinear with that of the adjacent pavilion
facet.
[0068] The vertex of each kite-shaped pavilion facet extends from a
corresponding girdle corner 99 to cutlet 69, such that the four
kite-shaped pavilion facets, as well as the four shortened pavilion
facets, converge thereto. As shown in FIG. 9, the pavilion facets
are provided with rotational symmetry about cutlet 69. By extending
sides 101 and 102 of each shortened pavilion facets 91, 93, 95, 97
until each side intersects with the other, corresponding imaginary
vertices 91V, 93V, 95V, 97V may be constructed, whereby imaginary
circle 103 whose center is cutlet 69 may be constructed from each
of the imaginary vertices. Imaginary circle 103 also coincides with
each girdle corner 99 and the vertex of the corresponding
kite-shaped pavilion facet. Enhanced brilliance and fire, as well
as appearance of a table reflection, is contingent upon this
rotational symmetry.
[0069] In addition to its rotational symmetry, pavilion 70 is
advantageously arranged with mirror symmetry. Without mirror
symmetry, the light which is reflected from the pavilion would not
be uniform, and one zone of the table may be darker than another
zone, thus detracting from the resulting fire. Referring now to
FIG. 8, lines of symmetry 105-108 are shown, whereby each line of
symmetry passes through cutlet 69. Lines of symmetry are
perpendicular to girdle 52 and divide each shortened pavilion facet
in two, while lines of symmetry 107 and 108 intersect opposite
girdle corners 99 and divide each kite-shaped pavilion facet in
two. Each lower hexagon facet and each set of lower hexagon facets
is provided with a mirror image with respect to the corresponding
line of symmetry. For example with respect to line of symmetry 106,
lower hexagon set 76 is the mirror image of lower hexagon set 83
and set 79 is the mirror image of set 80, while lower hexagon facet
78(a) is the mirror image of lower hexagon facet 81(b) and facet
77(a) is the mirror image of 82(b). Likewise with respect to line
of symmetry 107, set 78 is the mirror image of set 79 and set 76 is
the mirror image of set 81. To achieve this mirror symmetry, each
set of lower hexagon facets consists of a larger and smaller
triangular facet having a common side. The long end of the larger
facet is collinear with long side 88 of the adjacent kite-shaped
pavilion facet and one end of the smaller facet is collinear with
long side 89 of the adjacent shortened pavilion facet. The
remaining end of each lower hexagon facet is collinear with the
corresponding hexagon facet 72. Each lower hexagon facet is cut
with an angle ranging from 42-53 degrees, and preferably 50
degrees, with respect to table 55 (FIG. 7).
[0070] Hexagon facet 72 is adapted to provide a rectangular girdle
with a pavilion having rotational and mirror symmetry. One side of
each hexagon facet 72 is collinear with girdle 52. Four sides are
collinear with corresponding sides of four lower hexagon facets,
respectively, and the remaining sixth side is collinear with end 98
of the corresponding shortened pavilion facet. Each hexagon facet
is cut at an angle ranging from 52-60 degrees, and preferably at an
angle of 55 degrees with respect to table 55 (FIG. 7). The maximum
depth of each hexagon facet, measured by a perpendicular line from
girdle 52 to end 98 of the shortened pavilion facet, ranges from
25-30 percent, and preferably 27 percent, of the maximum girdle
length, i.e. measured in a plane parallel to table 55 (FIG. 7). The
minimum depth of each hexagon facet is 0 percent, at the point
coinciding with lower girdle border 51 (FIG. 11).
[0071] FIG. 10 illustrates the relative location of the facets of
the crown and the pavilion. The facets of the crown are indicated
by solid lines, whereas the facets of the pavilion are indicated by
dotted lines. It would be appreciated that lines of symmetry 105
and 106 connect the corresponding vertices of intermediate bezel
facets 58, which abut the corresponding midpoints of girdle 52, and
that cutlet 69 is located at the intersection of lines 105 and 106.
It has been surprisingly found that hexagon facet 72 does not
project into corner bezel facets 56, and as a result any blemish or
inclusion that would normally diminish the beauty and brilliance of
the diamond is not noticeable and is not reflected into the crown.
Even though hexagon facet 72 is not reflected into the crown, light
rays are nevertheless reflected through both corner bezel facets 56
and through intermediate bezel facets 58, due to the index of
refraction of the diamond, thereby precluding the appearance of any
shadows. In contradistinction to pavilion 47 of a Princess diamond
(FIG. 6) whose lower girdle facets cast shadows, hexagon facet 72
does not cast any shadow and does not diminish the brace of the
diamond.
[0072] FIG. 11 illustrates a side view of the diamond, in
accordance with the present invention. The crown height ranges from
33-44 percent, and preferably from 38-39 percent, of the maximum
girdle length. The crown angle ranges from 27-40 degrees, and
preferably from 33.0-35.0 degrees, with respect to table 55. The
pavilion depth ranges from 72-83 percent, and preferably from 77-78
percent, of the maximum girdle length.
[0073] Girdle 52 is shown to have a non-uniform height, ranging
from a minimum height at the lower vertex of corner bezel facet 56
to a maximum height at the lower vertex of intermediate vertex 58.
Since each side of girdle 52 is substantially perpendicular, i.e.
ranging from 86-94 degrees, and preferably 90 degrees, with respect
to table 55, its vertical projection, as shown in FIGS. 7-10, is a
line. Lower border 51 of the girdle is a line parallel to table 55;
however, the upper border of each side of the girdle is comprised
of four distinct segments each of which is collinear with the
neighboring upper girdle facets. Accordingly, lower vertex 59 of
intermediate bezel facet 58 is located at a height above that of
lower vertex 68 of upper girdle facet 65(a), for example. The
height of girdle 52 at girdle corner 99 ranges from 1-5 percent,
and preferably is 3 percent of the maximum girdle length, and at
vertex 59 ranges from 10-20 percent, and preferably 15 percent of
the maximum girdle length. FIG. 12, which is another side view of
the diamond at which girdle corner 99 is shown to be at an
intermediate point along lower girdle border 51, illustrates that
each side of the girdle is interconnected at the point of minimal
height.
[0074] FIG. 13 illustrates that crown 50 has a substantially round
cross section, cut along a plane parallel to table 55. Star facets
21, intermediate bezel facets 58 and corner bezel facets 56 are cut
at the predetermined angles, as described hereinabove, so as to
allow for a rounded gemstone with rotational symmetry about the
cutlet, thereby enhancing the brilliance and fire of the gemstone
and enabling the appearance of a table reflection. Similarly FIG.
14 illustrates that pavilion 70 has a substantially round cross
section, cut along a plane parallel to table 55 due to the
rotational symmetry of the pavilion and lower hexagon facets.
[0075] FIG. 15 is a picture of the pavilion of a rounded
rectangular gemstone that was produced in accordance with the
present invention, and FIG. 16 is a picture of the crown. FIG. 17
is a perspective view of the gemstone of the present invention
facing a girdle corner. FIG. 18 is a perspective view of the
gemstone of the present invention taken above the crown.
[0076] As can be appreciated from the above description, the
present invention demonstrates a novel gemstone exhibiting the
brilliance and fire of a Brilliant cut gemstone even though the
girdle is rectangular, when viewed thereabove or therebelow. It has
been surprisingly found that the material loss associated with the
gemstone of the present invention ranges from 30-40 percent of a
rough dodecahedron, in contrast to a Brilliant cut, which results
in a material loss of 40-50 percent of a rough dodecahedron. Novel
facets are employed to achieve rotational and mirror symmetry,
while being adapted to the structural limitation of a rectangular
girdle.
[0077] While some embodiments of the invention have been described
by way of illustration, it will be apparent that the invention can
be carried into practice with many modifications, variations and
adaptations, and with the use of numerous equivalents or
alternative solutions that are within the scope of persons skilled
in the art, without departing from the spirit of the invention or
exceeding the scope of the claims.
* * * * *