The invention relates to cut gems and articles including such gems.

It also relates to improvements made to cut gems so that they have optical characteristics of light reflection superior to those obtained with a gem cut in accordance with a known size "princess", so that the resulting brightness is more important .

The princess cut gems spread, including this one of the sizes that gives more shine like a diamond, just after the actual size "shiny".

US document 8,181,482 is known a gem the size of which is made of a princess cut, which recalls the shape of a butterfly.

The cut gem described in this document comprises:

- a girdle having four sides and four vertices of girdle girdle,

- a table made by a flat facet,

- a ring which extends between the table and the girdle, in a first direction,

- and a cylinder head which extends in a second direction opposite to said first direction, between said girdle and a yoke tip.

The invention aims to provide an alternative cut gem, with particularly brightly.

It proposes for this purpose a cut gem of the genre in question, which is remarkable in that the ring has twenty-four facets, the yoke has thirty two sides and that the four sides of girdle are identical in form of arch circle with its concavity facing outwards of the gem.

Thus produced, the gem has a brightness more pronounced than that obtained with a gem as described in US 8,181,482.

According to the invention, the gem may also include the features presented below, taken separately or in combination.

Regarding the crown, it may include:

o four corner table facets positioned around the table,

o four sides, each of the four sides of the ring comprising:

- at least one cutout,

■ a first crown star facet positioned between the cut-off and a first facet table corner, and

■ a second ring star facet positioned between the cut and a second table facet corner.

Within this embodiment, it can be expected that twenty four facets of the crown have four sides, four bezels, four cuts, eight star facets and four corner table facets.

In addition, according to an embodiment that will be presented later, we get a particularly important luster with a gem carved in which:

- the table is part of a table map,

- each bezel fits into a bezel map,

and wherein a bezel plane is inclined relative to the table plane at an angle substantially between 35 and 39 °.

Regarding the cylinder head, it may include:

o four cylinder pavilions,

o a yoke star having four yoke star facets connecting the yoke tip and peaks girdle, and o at least three bolt fences positioned on either side of each facet yoke star, between a cylinder head star facet and a pavilion among said four flags.

Within this embodiment, it can be expected that the thirty-two pavilion facets comprise four cylinder pavilions, four bolt star facets and twenty-four cylinder fences.

In addition, according to an embodiment that will be presented later, we get a particularly important luster with a gem carved in which:

- the table is part of a table map,

- each flag is part of a flag map,

and wherein each flag plane is inclined relative to the table plane at an angle substantially between 58 and 62 °.

To get even better brightness, cut gem can be performed with the following features:

- each of the sides of the girdle comprises a side length of girdle which is the shortest distance taken between two vertices of adjacent girdle,

- said yoke star has a basic square cross-section in the vicinity of the yoke tip,

and wherein the base of square cross-section has a diagonal whose length is substantially between 5 and 1 1% of the side length of girdle, preferably between 5.5 and 10.5%.

The cut gem may also include the following features:

- each of the sides of the girdle comprises a side length of girdle which is the shortest distance taken between two vertices of adjacent girdle,

- each of the sides of girdle has a maximum depth, taken perpendicularly to a line connecting two peaks adjacent girdle,

and wherein said maximum depth substantially corresponding to between 5.5 and 9, 5% of said length of a side of girdle.

In addition, the cut gem may also include the following features:

- each of the sides of the girdle comprises a side length of girdle which is the shortest distance taken between two vertices of adjacent girdle,

- the table has eight table tops, including four table tops are also highs table corners and four other peaks, alternating with peaks of table corners, are also cut tops,

and wherein the distance measured between a top cut and the line connecting the two vertices of adjacent girdle perpendicular to said straight line, is substantially between 18 and 22% of said length dimension of girdle.

In accordance with one embodiment of the invention, the gem is a diamond.

The invention also relates to a jewelry article having at least one gem as defined above.

To be executed, the invention is exposed to sufficiently clear and complete way from the following description which is, in addition, accompanied by drawings in which:

- Figure 1 shows a gem according to an advantageous embodiment of the invention, in top view,

- Figure 2 shows the rock shown in Figure 1, seen from below,

- and Figure 3 shows the rock illustrated in Figures 1 and 2, in side view.

In the following description, the terms "lower," "upper", "top", "bottom" etc .. are used in the drawings for greater ease of understanding. They should not be understood as limitations of the scope of the invention.

The gem illustrated in Figures 1 to 3 is made from a princess cut diamond (that is to say, a diamond whose general shape is similar to a pyramid the base of which is square in shape). However, it will be easy for the skilled person to perform the special stone that will be described, other precious or semi precious stones.

In the following description, it will be first referred to a top of the rock, that is to say the part of the gem that it is customary to present to the outside of a jewel when the gem is secured to the jewel. This is the part of the visible gem by an observer.

The upper part of the gennnne comprises, in conventional manner, a gem table formed by a flat facet and a ring surrounding the table and formed of several contiguous facets. The crown extends substantially along a first direction H (see Figure 3).

In contrast, the lower part of the gem faces the jewel will be called the head of the gem. The cylinder head extends in a direction B opposite to the direction H and will be described subsequently with reference to Figure 2.

Figure 1 shows a top view of a gemstone in accordance with the invention, and thus an upper portion of the gem, whose general shape is substantially square.

We will call "girdle" the widest portion of the gem to give its diameter: Gem shown in Figs thus has a girdle 3 of substantially square shape having four vertices 1 (referred to hereinafter as vertices of girdle) connected together by four sides 2 of the same length girdle.

As can be seen in Figure 1, each of the four sides of girdle 2 is in the shape of a circular arc (concave) whose concavity is facing outwardly of the gem.

Figure 3 illustrates a side 2 of girdle 3 of the gem, the girdle 3 is shown schematically in broken lines between the two vertices of girdle 1 in Figure 3.

The center of the upper part of the rock shown in Figure 1, is a table 4 of octagonal shape. Four vertices of the four octagonal table align with the peaks of girdle 1 according to a diagonal D1 or D2 of the girdle, and constitute the vertices 5 table corner. Other peaks of the table 4 alternate with the tops 5 table corner and are tops 6 cut.

Each of the sides 2 of girdle 3 has a length L side of girdle, which is the shortest distance taken between two adjacent peaks 1 girdle.

6 cut vertices are each equidistant from two adjacent vertices 1 girdle. The position of a vertex is cut 6

selected on a line D4, which is perpendicular to the line connecting the two vertices D3 girdle 1 and which passes through the center C of the segment connecting the two vertices 1 girdle. The distance L1 between the center C and the top 6 of cut is chosen such that it is substantially between 18 and 22% of the length L of the side 2 of girdle.

In the example illustrated in Figure 1, the distance L1 between the center C and the top 6 of cleavage corresponds to substantially 20% of the length L between two vertices 1 girdle.

The depth L2 of the concavities of the two sides of girdle is also chosen according to the length L shorter engagement between two vertices of girdle 1 (see Figure 1).

The depth L2 corresponds to approximately between 5.5 and 9.5% of the length L of a side 2 of girdle (see Figure 1).

Between the table 4 the sides 2 of girdle 2 is formed the crown 7 of the gem (see Figures 1 and 3).

The ring 7 comprises, in the example illustrated in the figures, four side faces 8 which correspond to the four faces along the profile of the curvature of the sides 2 of girdle (see Figure 3).

Four corners of the table 4, the ring 7 has four facets 9 corner tables substantially diamond-shaped, one of the peaks is performed by a table top 5 and a corner opposite vertex is formed by a top 1 of girdle. The other two peaks of facets 9 table corner are referenced T in Figure 1.

The crown also comprises four bezels 10 formed by facets defined between two vertices of adjacent girdle 1 and two T tops of the two facets 9 of adjacent edges of tables, one associated with the vertices of adjacent girdle and considered.

The inclination of the bezels relative to the table top 4 is such that P1 of bezels plane makes an angle a with the plane P2 in which the table 4 is registered, the angle a is between 35 and 39 ° ( substantially 37 ° in connection with the example illustrated in Figure 3).

The ring 7 also has four facets called cuts 1 1 of triangular shape, located between the bezels and the table 4, and having vertices two vertices 7 (in common with the bezels 10) and the top 6 of cut (in common with table 4).

Finally, between the four facets 9 of table corner, the table 4 and the cuts 1 1 crown has eight star facets 12, each of triangular form, so called because they form a star around the table 4.

Thus produced, the gem according to the invention and shown in the figures comprises a ring 7 which comprises twenty-four facets in total.

It will now be referred to the head of the gem of the invention, with particular reference to Figure 2.

The yoke 13 extends between the girdle 3 and a yoke tip 14 it contains. The girdle 3 being of substantially square shape, the yoke 13 has substantially the shape of a pyramid the base of which is square.

The yoke 13 includes a yoke 15 star having four branches connecting the yoke tip 14 and each of the vertices of one girdle. The four branches of the breech stars are called "bolt star facets 16".

Each of the arms has a wide base 17 and a narrow top, spike shaped 18, which connects the top of girdle. The wide bases of the four cylinder head 17 of star facets 16 form the four abstract sides of a square (shown in dotted lines) whose center is formed by the yoke tip

14 (see Figure 2).

In other words, in the vicinity of the bolt tip 14, the breech star

15 shows a base 19 of square section.

In accordance with a feature of a gemstone according to the invention, the base

19 has a diagonal 20 whose length is between 5 and 1 1% of the length L from the side of girdle, preferably between 5.5 and 10.5%. In this example, the diagonal length 20 is substantially equal to 8% of the length L.

Further star yoke 15, the yoke 13 has four bolt lodges 21 contiguous to the lateral faces 8.

Each yoke flag 21 is realized by a facet plane at three sides: a first side 22 is curved and is common with a side of the face

8. A lateral second and third sides 23 and 24 are of the same length and each of the second and third sides connects an apex of girdle 1 to a point 25 located on a straight line bearing the diagonal 20.

The position of point 25 on the right bearing the diagonal 20 is determined by the orientation of a plane P3 of the flag relative to the table plane P2 4: according to the invention, the plane of tilt angle β P3 relative to the plane P2 is substantially of 60 ° (plus or minus 2 ° - see Figure 3).

Between a head flag 21 and a yoke star facet 16 are provided three facets of breech fences 26.

Each yoke end facet 26 is triangular in shape with a base 27 which is supported by the right bearing the diagonal 20 and two sides connecting the base 27 to a peak of one girdle.

The three yoke 26 and fences 27 have three bases aligned along the straight line bearing the diagonal 20 and the point 25. Depending on the position of the yoke end facet 26, it also comprises a common side with a cylinder star facet 16, or with a yoke 21 flag or no side joint if the breech closing facet 26 is located between two other facets closing yoke 26.

In total, the yoke 13 comprises twenty-four breech end facets 26, 27 which is having a common basis for two yoke end facets 26 which are the image from one another by axial symmetry whose axis corresponds to the right on the diagonal 20.

Thus completed, the head of the gem shown in the figures includes thirty-two facets including twenty-four breech end facets 26, four pavilions 21, and four bolt star facets 16.

The invention is not limited specifically the gem just described. Furthermore, the invention extends to any jewelry article comprising at least a gem such as that particularly described and illustrated above

CLAIMS

1. Gemstone cut having

- a girdle (3) having four sides (2) and four vertices of girdle (1) of girdle,

- a table (4) formed by a flat facet,

- a ring (7) which extends between the table (4) and the girdle (3), along a first direction (H),

- and a yoke (13) extending in a second direction (B) opposite to said first direction (H) between said girdle (3) and a yoke tip (14),

said gemstone being characterized in that the ring (7) comprises twenty-four facets, the cylinder head (13) comprises thirty-two facets and in that the four sides (2) of girdle are identical in shape of a circular arc whose concavity is oriented towards the outside of the gem.

2. Gem cut according to claim 1, wherein said ring (7) comprises:

o four corner table facets (9) positioned at the four corners of the table (4)

o four sides, each of the four sides of the ring comprising:

■ at least one cut (1 1),

■ a first star facet (12) positioned between the crown break (1 1) and a first side corner of the table (9), and

■ a second star facet (12) positioned between the crown break (1 1) and a second facet corner of the table (9).

3. Gem cut according to claim 2, wherein the twenty-four facets of the crown (7) have four side faces (8), four bezels (10), four cuts (1 1), eight star facets (12) and four corner table facets (9).

4. Gem cut according to claim 3, wherein:

- the table (4) is part of a table plane (P2),

- each bezel (10) is part of a bezel plane (P1),

and wherein a bezel plane (P1) is inclined relative to the table plane (P2) an angle (a) substantially between 35 and 39 °.

5. Gemstone according to any one of claims 1 to 4, wherein said cylinder head (13) comprises:

o four bolt lodges (21)

o a yoke spider (15) having four yoke star facets (16) connecting the yoke tip (14) and peaks (1) of the girdle (3), and

o at least three bolt fences (26) positioned on either side of each facet yoke spider (16) between a yoke star facet (16) and a flag (21) of said four wings (21).

6. Gem cut according to Claim 5, wherein the thirty-two pavilion facets (13) include four cylinder flags (21), four yoke star facets (16) and twenty four yoke fences (26).

7. Gem cut according to any one of claims 5 or 6, wherein:

- the table (4) is part of a table plane (P2),

- each hub (21) is part of a roof plane (P3)

and wherein each flag plane (P3) is inclined relative to the table plane (P2) an angle (β) substantially comprised between 58 and 62 °.

8. cut gemstone according to any one of claims 5 to 7, wherein:

- each of the sides (2) of girdle has a length (L) side of girdle which is the shortest distance taken between two crests (1) of adjacent girdle,

- said yoke spider (15) has a base (19) of square section in the vicinity of the yoke tip (14),

and wherein the base (19) of square section presents a diagonal (20) whose length is substantially between 5 and 1 1% of the length (L) side of girdle.

9. cut gemstone according to any preceding claim, wherein:

- each of the sides (2) of girdle has a length (L) side of girdle which is the shortest distance taken between two crests (1) of adjacent girdle,

- each of the sides (2) of girdle has a depth (L2) maximum, taken perpendicularly to a line connecting the two peaks (1) of adjacent girdle,

and wherein said depth (L2) corresponds to substantially maximum between 5.5 and 9, 5% of said length (L) on one side of girdle.

10. Gem trimmed according to any preceding claim, wherein:

- each of the sides (2) of girdle has a length (L) side of girdle which is the shortest distance taken between two crests (1) of adjacent girdle,

- the table (4) has eight table tops (5, 6), including four table tops are also the peaks of Table corners (5) and four other peaks alternating with peaks table corners (5) , are also cut-off tops (6)

and wherein the distance (L1) between an intake cutoff top (6) and the line connecting the two peaks (1) of adjacent girdle,

perpendicular to said straight line, is substantially between 18 and 22% of said length (L) of side (2) of girdle.

January 1. Cut gem according to one of the preceding claims, the gem is a diamond.

12. Article of jewelry comprising at least a gemstone according to any preceding claim.