HK1210680B - Cushion cut gemstone with excellent optical brilliance - Google Patents

Abstract

A gemstone including a substantially rectangular girdle with rounded corners, a crown extending in a first direction from the girdle, and a pavilion extending in a second direction from the girdle opposite the first direction. The gemstone has 69 uniquely arranged and angled facets, 41 of which are in the crown, and 28 of which are in the pavilion. The height of the crown is preferably between 12 to 19 1/2 % of the width of the stone, the total depth of the stone is preferably between 58-68% of the width of the stone, and the width of the table is preferably between 55-65% of the width of the stone.

Description

Pad-shaped cut gemstone with excellent optical brightness

Technical Field

The present invention relates to a pad-shaped cut gemstone exhibiting excellent optical brightness. In particular, the present invention relates to a pad cut diamond having superior optical properties compared to those of an industry standard pad cut diamond.

Background

One of the main properties of a diamond is its optical return or light performance, i.e., the amount of light that returns from the diamond to the eye. The higher the light performance rating, the better the brilliance (white) and fire (colored) of the diamond. Wherein the optical performance is also affected by the number, shape, angle and arrangement of facets on the cut diamond. However, merely increasing or decreasing the number and angle of facets has no direct correlation with the increase in optical performance. In fact, sometimes an increase in the number of facets may result in a dull and sparkless diamond, just contrary to what is desired. Only an accurate and precise combination of angles and facets together creates a perfect solution with the highest optical return.

A pad cut diamond is a diamond shape popular in the beginning of the 19 th century, so named because it closely resembles a plump pad or pillow. The Cut prior to the mat Cut is a so-called Old Mine Cut (Old Mine Cut), which is a square Cut with rounded corners, a deep Cut with a high crown, a small top Cut plane and a large facet. The old mine cut has 33 crown and 25 pavilion facets.

Many of the best known gemstones in the world are pad cut, including blue Hope diamonds (45.52 carats), Regent diamonds (140.5 carats) and yellow Tiffany diamonds (128.54 carats). The world's largest cut sapphire, 423 carat of Logan sapphire at smith natural history museum, is pad cut.

Pad cut diamonds have gained popularity in recent years as a more unique alternative to traditional round drill cutting. A typical pad cut diamond contains 58 to 64 facets. However, even with this number of facets, typical pad cut diamonds available to consumers lack sparkle and brilliance compared to round cut diamonds.

Disclosure of Invention

It is therefore an object of the present invention to enhance the brightness of pad cut diamonds so that they are comparable to the brightness and light performance of ideal round brilliant cut diamonds.

It is another object of the present invention to make the cut gemstone appear larger than a typical modified pad-shaped cut gemstone. In particular, the pad cut diamonds of the present invention typically appear 10% larger than typical modified pad cut gemstones because the additional "half-moon" facets of typical modified pad cut gemstones are not present.

The pad-shaped cut diamond of the present invention comprises a waist portion of a generally rectangular, preferably square shape; a crown extending from the waist in a first direction; and a pavilion extending from the girdle in a second direction opposite to the first direction. The mat cut diamond had 69 uniquely arranged and angled facets, 41 of which were in the crown and 28 of which were in the pavilion. The height of the crown is preferably between 12 and 19 and one-half% of the width of the stone, the overall depth of the stone is preferably between 58-68% of the width of the stone, and the width of the top table is preferably between 55-65% of the width of the stone.

The crown has four sides, rounded corners, a top table, eight star facets around the top table, four side kite facets located between two star facets on each side of the gemstone, four corner kite facets located between opposing star facets at each corner of the gemstone, and 24 top half facets around the girdle.

In a preferred embodiment, the eight star facets are cut at an angle of about 21-31, the four side kite facets are cut at an angle of about 35-45, the four corner kite facets are cut at an angle of about 30-40, and the top half facets are cut at an angle of about 40-50. All of these angles are relative to a plane parallel to the top tangent plane surface.

The 28 facets of the pavilion include four main pavilion facets extending from each respective corner of the gemstone to the bottom surface, and six (6) lower half facets between each of the four main pavilion facets. Preferably, and with respect to a plane parallel to the girdle surface, the four main pavilion facets are each at an angle of about 34-38 °, and the lower half facets are each at an angle of about 35-43 °.

The unique combination of angles and facets of the present invention results in excellent fire and brightness. In particular, the unique facet and angle adoption and placement of the present invention achieves an average of up to 95% ("excellent") light performance in terms of Gemstone Certification and Assurance Laboratories (GCAL). Furthermore, unlike standard pad cut diamonds, which employ industry standard 58 to 64 facets, the present invention employs a unique combination of 69 facets (41 facets on the crown and 28 facets on the pavilion) that achieves the "pad brilliance" rating of the american institute of Gemstones (GIA) with excellent polishing and excellent symmetry. This is an unexpected and highly beneficial grade for pad cut diamonds.

Drawings

The figures are for illustrative purposes only and are not necessarily drawn to scale. The invention itself, however, will be best understood by reference to the following detailed description when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side view of a gemstone according to the present invention;

FIG. 2 is a top plan view of the gemstone shown in FIG. 1; and

fig. 3 is a bottom view of the gemstone shown in fig. 1.

Detailed Description

The invention will be illustrated with reference to the figures. Such figures are intended to be illustrative rather than limiting and are included herein to facilitate explanation of exemplary features of embodiments of the present invention. Unless otherwise indicated, the drawings are not drawn to scale and are not intended for use as engineering drawings.

Referring now to the drawings, figure 1 is a side view of a pad shaped cut diamond 1 according to the present invention. Although the following description refers to a pad cut diamond, it will be readily apparent to those skilled in the art that the unique angles and facets described herein may be applied to any precious or sub-precious gemstone.

As shown in fig. 1, a pad-shaped cut diamond 1 includes a substantially rectangular girdle 2 having rounded corners 3, a crown 4 extending upward from the girdle 2, and a pavilion 5 extending downward from the girdle 2. It is preferred that the cut diamond 1 has an aspect ratio of greater than or equal to 1. For example, for a mat cut diamond with a square appearance, it is preferred that the aspect ratio is between 1 and 1.05; and for pad cut diamonds with more rectangular shapes, it is preferred that the aspect ratio be greater than 1.15. It is also preferred that the thickness of the waist is 1% to 7% of the width W of the stone, i.e. "thin to very thick". The crown 4 has a height CH of about 12 to 19 and one-half of the gemstone width W (all percentages being based on the gemstone width W being equal to 100%). The total depth D of the gemstone is about 58-68% of the width W of the gemstone.

Fig. 2 is a top view showing the crown 4 of the mat-shaped cut diamond of fig. 1. As shown in fig. 2, the crown 4 includes 41 unique angled and arranged facets. The 41 facets include a top table 6, eight star facets 8 around the top table 6 (two star facets on each side of the stone), four side kite facets 10 on each side of the stone between the two star facets 8, four corner kite facets 12 at each corner 3 of the stone between the opposite star facets 8 and twenty-four upper half facets 14 around the girdle 2. Preferably, a set of three upper half facets 14 is located between the kite facet 10 and the corner kite facet 12 of each side. As shown in fig. 1, top table 6 has a width TW that is between 55-65% of the width W of the gemstone.

In a preferred embodiment, the eight star facets are cut at an angle of about 21-31, the four side kite facets are cut at an angle of about 35-45, the four corner kite facets are cut at an angle of about 30-40, and the top half facets are cut at an angle of about 40-50. All of these angles are relative to a plane parallel to the top tangent plane surface. The particular shape, size and angle of these facets relative to a plane parallel to the surface of the top table 6 will depend on the symmetry and size of the gemstone being cut.

Given the above arrangement of crown facets, and as shown in fig. 2, each respective side of the crown 4 is defined and bounded by two respective corner kite facets 12, and includes two star facets 8, a side kite facet 10, and six upper half facets 14. Furthermore, and as shown in fig. 1 and 2, the corners 3 of the pad-shaped cut diamond are rounded. The particular radius of the corner 3 is not limited.

Turning now to fig. 3, there is shown a pavilion 5 of the cut diamond 1 shown in fig. 1. Pavilion 5 includes 28 unique angled and arranged facets. The 28 facets comprise four main pavilion facets 16 extending from each respective corner 3 of the cut diamond 1 to the bottom surface 18. Specifically, each of the four main pavilion facets 16 extends from a position corresponding to the apex of the corner kite facet 12 to a bottom surface 18. These main pavilion facets 16 are preferably cut at an angle of about 34-38 deg. with respect to a plane parallel to the surface of the girdle 2. Although the present invention is not limited to the type of pavilion used, the pavilions 18 are preferably pointed pavilions (i.e., 0% of the width of the stone) to substantially flat pavilions having an area of 3% or less of the width of the stone.

Between each of the four main pavilion facets 16, the gemstone is divided into six (6) lower half facets (24 lower half facets in total). These lower half facets 20 are preferably cut at an angle of about 35-43 deg. with respect to a plane parallel to the surface of the waist 2. However, the particular shape, size and angle of the lower half facet 20 relative to a plane parallel to the surface of the girdle 2 will depend on the symmetry and size of the gemstone being cut.

Preferably, the six (6) lower half facets are further divided into two lower half facets 20A and 20F near the main pavilion facet, two lower half facets 20C and 20D far from the main pavilion facet, and intermediate lower half facets 20B and 20E between each of the near lower half facet and the far lower half facet. The outermost lower half facets 20A and 20F, which are closer to the main pavilion facet 16, are preferably cut at an angle of about 35-40, the middle lower half facets 20B and 20E are preferably cut at an angle of about 37-42, and the middle lower half facets 20C and 20D, which are further from the main pavilion facet 16, are preferably cut at an angle of about 38-43.

The unique combination of angles and facets of the present invention results in excellent fire and brightness. In particular, the adoption and arrangement of the unique facets and angles of the present invention achieves an average of up to 95% ("excellent") optical performance, and a "mat brightness" rating of the american institute of Gemstones (GIA) with excellent polishability and excellent symmetry, in accordance with the Gemstones Certification and Assurance Laboratory (GCAL). Thus, unlike standard pad cut diamonds, the present invention employs a unique combination of 69 facets (41 facets in the crown and 28 facets in the pavilion).

Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications will become apparent to those skilled in the art. Accordingly, the invention is not to be limited by the specific disclosure herein, but only by the appended claims. For example, while the invention has been described with respect to cut diamonds, the unique angles and facets can be equally applied to all precious or sub-precious gemstones to achieve enhanced brightness and light performance. The invention also includes a jewelry set having such gemstones.

Claims (14)

1. A gemstone, comprising:

a generally rectangular waist having rounded corners;

a crown extending in a first direction from the waisted portion, the crown having a top tangent plane, four sides, and four corner kite facets each positioned at a respective rounded corner, each of the four sides comprising:

two star facets adjacent to the top tangential plane;

a lateral kite facet located between two star facets;

a first set of three upper half facets located on a first side of the side kite facets; and

a second set of three upper half facets located on a second side of the side kite facets; and

a pavilion extending from the girdle in a second direction opposite to the first direction, wherein:

the height of the crown is between 12 and 19 and one-half% of the width of the stone;

the width of the top table is between 55-65% of the width of the gemstone;

the four corner kite facets are angled at 30-40 ° with respect to a first plane parallel to the top tangent plane surface, the two star facets are angled at 21-31 ° with respect to the first plane, the side kite facets are angled at 35-45 ° with respect to the first plane, and the first set of three upper half facets and the second set of three upper half facets are angled at 40-50 ° with respect to the first plane;

the pavilion includes four main pavilion facets and six lower half facets between each of the four main pavilion facets, each main pavilion facet extending from a corresponding rounded corner to a pavilion bottom;

four main pavilion facets each angled at 34-38 ° relative to a second plane parallel to the girdle surface; and

the six lower half facets are each angled at 35-43 deg. relative to the second plane.

2. The gemstone according to claim 1, wherein each of the four main pavilion facets extends from a position corresponding to an apex of the respective corner kite facet.

3. The gemstone according to claim 1 or 2, wherein the bottom of the pavilion is the bottom surface of the gemstone.

4. The gemstone according to claim 3, wherein the pavilion has a region of 3% or less of the width of the gemstone.

5. The gemstone according to claim 1 or 2, wherein said waist is substantially square.

6. The gemstone according to claim 1 or 2, wherein the gemstone has an aspect ratio of 1 or greater.

7. The gemstone according to claim 6, wherein said aspect ratio is between 1 and 1.05.

8. The gemstone according to claim 6, wherein said aspect ratio is greater than 1.15.

9. The gemstone according to claim 1 or 2, wherein the depth of the gemstone is between 58-68% of the width of the gemstone.

10. The gemstone according to claim 1 or 2, wherein the thickness of the waist is 1% to 7% of the width of the gemstone.

11. The gemstone according to claim 1 or 2, wherein the gemstone has an average 95% optical performance characteristic.

12. The gemstone according to claim 1 or 2, wherein the six lower half facets comprise:

two lower half facets adjacent to the main pavilion facet and angled at 35-40 ° with respect to the second plane;

two lower half facets, distal from the main pavilion facet and angled at 38-43 ° with respect to the second plane; and

a middle lower half facet angled between each of the proximal lower half facet and the distal lower half facet at an angle of 37-42 ° relative to the second plane.

13. The gemstone according to claim 1 or 2, which is a precious gemstone.

14. A piece of jewelry having disposed therein one or more gemstones according to any one of the preceding claims.