Oh, patents! Louis Vuitton's proprietary star cut diamond

Copyright © Françoise Herrmann

The House of Louis Vuitton (LV) patented its own proprietary diamond cut, called the Star cut. The LV Star diamond cut was inspired by the iconic Louis Vuitton Monogram flower.

The Louis Vuitton Star diamond cut invention is recited in a family of patents, that includes the US utility patent US2017303647 (A1), titled Cut gem and article comprising such a gem. The patent was granted on October 26, 2017, to Eric Hamers, the French inventor. The patent application was filed by Louis Vuitton Malletiers, in France.

The invention seeks to surpass the brilliance of Princess-cut diamonds by promoting greater light reflection, thereby increasing diamond brilliance. For this purpose, the Louis Vuitton Star-cut diamond has a crown with twenty-four facets, a pavilion with thirty-two facets, and four girdle sides that are identical, each with the distinctive form of an arc of a circle. 

Below, an LV diamond solitaire ring, centered with a Monogram Star-cut diamond, and the Star-cut patent Figure 2, showing a bottom view of the LV Star-cut diamond. The scope of the invention extends to gems other than diamonds.

The Abstract of the invention is included below:

The invention relates to a cut gem comprising a girdle (3) having four girdle sides (2) and four girdle corners (1), a table (4) realized by a flat facet, a crown (7) which extends between the table (4) and the girdle (3), in a first direction (H), and a pavilion (13) which extends in a second direction (B), opposite to said first direction (H), between said girdle (3) and a tip of the pavilion (14). The gem is noteworthy in that the crown (7) has 24 facets, the pavilion (13) has 32 facets and in that the four girdle sides (2) are identical in the form of an arc of a circle, the concavity of which is oriented towards the outside of the gem. [Abstract US2017303647 (A1)]

Reference

Louis Vuitton deep-time high jewelry

https://hk.louisvuitton.com/eng-hk/stories/deep-time-high-jewellery

Oh, patents! Wueste's princess cut diamond

Copyright © Françoise Herrmann

The princess cut diamond is sometimes referred to as a square/rectangular modified brilliant-cut diamond, per the GIA (Gemological Institute of America) grading reports. It may be cut as a square or a rectangle. In general, square/rectangular princess cut diamonds use more of the rough diamond than round brilliant-cut diamonds. In turn, the amount of rough diamond waste that is generated impacts pricing. 

The princess cut diamond is recited in US6745596B2, titled Princess cut diamond, granted to Robert J. Wueste. Within the long prior art of diamond cutting, where round brilliant diamond cutters are always seeking the perfect diamond geometry in view of enhancing the diamond’s most prized properties, its essential brilliance, fire and scintillation, Wueste seeks to do likewise for the princess cut. Wueste seeks to find the perfect balance of the diamond’s essential properties, increasing the number of facets, recombining the shape of the crown, girdle and pavilion and their characteristic dimensions.

Wueste’s princess cut diamond has 101 facets (including the table) as summarized in the following abstract of the patent:

A princess cut gemstone having a pavilion, a girdle, and a crown. In the presently preferred embodiment, the princess cut gemstone is a diamond with 101 facets: a pavilion of 64 facets, a girdle of 4 facets, and a crown with 33 facets (including the table). [Abstract US6745596B2]

More specifically, in the preferred embodiment,  Wueste’s princess cut diamond  “comprises 8 side crown facets, 24-star crown facets, and a table facet. The pavilion comprises 20 side pavilion facets and 44-star pavilion facets. The girdle comprises 4 girdle facets".

Typical dimension ranges of a princess cut diamond are recited per the following table, extracted from the patent. Wueste’s preferred, and recited dimension ranges, for the patented princess cut diamond, are added in a fourth column --just in case you are wondering what the differences might be.

Name	Dimension	Value range	Wueste value range
Crown height  (percentage)	Percentage of crown's height to the overall width of the diamond	-5%-15%	8%  - 14%
Table percentage	Percentage of table's, vidth to the overall width of the diamond	-56%--82%	65%-85%
Depth percentage	Ratio of the overall depth of the diamond to the overall width of the diamond	-53%--85%	62%-75%
Length-to-Width Ratio	Ratio of the overall length of the diamond to the overall width of the diamond	-1:1-1.5:1	1:1-1 – 1:3-1

The patent also recites all the preferred angles for each of the crown, girdle and pavilion facets. Wueste also notes that since these are preferred dimensions and geometries, many variations, known to those skilled in the art, also fall within the scope of the invention.

The patent figure 3B is included above. It shows a bottom view of the invention square princess cut diamond, with the 44-star cut pavillion, according to the specifications of the patent. Figure 2B of the prior art is also included below it for you to see the bottom view differences in cut between the prior art 50-faceted (table included) conventional square princess cut, and the present invention reciting Wueste's 101-faceted princess cut diamond. An image of a marketed square princess cut diamond is also included above. 

Oh, patents! Wueste's brilliant-cut diamond

Copyright Françoise Herrmann

Robert J. Wueste's brilliant-cut diamond invention is recited in the lapsed US utility patent US6698239, titled Brilliant-cut diamond and method of forming thereof. 

The Wueste brilliant-cut diamond patent recites a varying number of facets. Per the abstract of the patent, the number of facets depends on how the facets are counted -- including or excluding the table;  in reference to the crown, or to both the pavilion and the crown.  Thus, for example, the brilliant-cut patent recites a preferred embodiment comprising a crown with 56 facets (excluding the table), and 114 facets including the pavilion. Whereas in another preferred embodiment, the patent recites a crown comprising with 64 facets (excluding the table) and 122 facets including the pavilion, per the following:

A brilliant-cut gemstone having a pavilion, a girdle, and crown is disclosed. The pavilion of the gemstone has 56 facets: specifically, 8 lower diamond-shaped facets, 16 middle kite-shaped facets, and 32 upper triangular facets. The girdle and table may be formed of one or more facets. In one preferred embodiment, the total number of crown facets (excluding the table) is 56, making a total of 114 facets (including the table). In another preferred embodiment, the total number of crown facets (excluding the table) is 64, making a total of 122 facets (including the table). [Abstract US6698239]

According to Wueste, the brilliant-cut sets the standard for diamond cuts, and accounts for 75% of diamonds sold worldwide. The brilliant-cut is also used for different sorts of gemstones, but it is specifically recited for diamonds in this patent.  

The patent discloses the significance of a diamond cut, which impacts the diamond’s appearance, giving it brilliance, fire and scintillation. Thus, the number of facets of a diamond is significant because facets can increase the brilliance of a diamond. The brilliance of a diamond is “how much it shines”. Brilliance is a function of the refractive index of diamonds, which is the highest of all gemstones, and of the geometry of the cut, which can maximize the amount of light reflected back out through the crown of the diamond, after it has entered the pavilion, through the table. Once light is reflected, it disperses into the seven rainbow colors of the visible light spectrum, resulting in what is called the fire of a diamond, also facilitated by the angle of the facets. Scintillation is the glittering effect of reflected light, when there is movement (of the diamond or the observer), in turn, a function of the size, cut, polish, and angle accuracy of the facets.

The theory of diamond optics, or of the impact of diamond cutting on the desirable characteristics of brilliance, fire and scintillation, is usually traced back to Marcel Tolkowsky’s Ideal Cut.  An Ideal Cut whose proportions were presented, in 1919, in a book titled Diamond Design:  A Study of the Reflection and Refraction of Light in a Diamond, itself part of Tolkowsky’s doctoral dissertation on diamond grinding, at the University of London. A book, which in turn would inform the American Gem Society (AGS) Standards for grading and evaluating diamonds, according to 4Cs: Cut, Color, Clarity and weight in Carats.

Notwithstanding the scientific optical foundation of diamond cutting, with explicit proportions and an Ideal Cut standard, diamond cutters are always striving to exceed the Tolkowsky-inspired AGS standards -- increasing the number of facets, and varying the angles at which the facets are cut, using new tools to streamline the process.  Robert J. Wueste’s brilliant-cut, as recited in US6698239, is no exception.  An ever more brilliant, scintillating and fiery diamond will always be needed.


The included extracted patent figures show a top view of the crown (fig. 3B) and a bottom view of the pavilion (fig. 2A) of one embodiment of Wueste's brilliant-cut diamond, together with the image of a brilliant-cut diamond. 

Reference

Tolkowsky, M. (1919) Diamond design: A Study of the Reflection and Refraction of Light in a Diamond.

http://www.folds.net/diamond_design/index.html

Oh, patents! My girl™ diamond cut

Copyright © Françoise Herrmann

Yair Shimansky's 8-sided square-cut diamond with a diamond-shaped table, and a faceted pavilion which also reflects light, is trademarked the My girl™ diamond cut.

The Shimansky My girl™ diamond cut was granted US Design patent USD490741, titled Gemstone. As a reminder :

“a utility patent” protects the way an article is used and works (35 U.S.C. 101), while a “design patent” protects the way an article looks (35 U.S.C. 171) [MPEP Chapt. 1502.01; [R-07.2015]].

The included patent figure 1 shows a top view of the diamond-shaped table. The patent Figure 2 shows the faceted edges of the pavilion from the bottom of the gemstone. Included below, the image of a marketed My girl™ cut diamond. 

References
Shimansky

http://www.shimansky.com/

MPEP – Chapt. 1502-01 – Distinction between design and utility patent

https://www.uspto.gov/web/offices/pac/mpep/s1502.html

Terminology - Diamond anatomy

Copyright © Françoise Herrmann

The Capetown Diamond Museum offers comprehensive diamond terminology, imported below, with added bilingual (French terminology).

• Table (table): Largest facet of a diamond, always flat like a table. 
• Crown (couronne): Top part of a diamond
• Girdle (rondiste): Outer perimeter and widest section of a diamond, where crown and pavilion meet. 
• Pavilion (culasse): Lower part of a diamond. Bridges girdle and culet.
• Culet (colette): Smallest facet of a diamond, located at the very tip.

References

Capetown Diamond Museum 

http://www.capetowndiamondmuseum.org/

Canada Bureau de la traduction - Translation bureau -  Diamond cutting vocabulary - Vocabulaire de la taille du diamant

http://publications.gc.ca/collections/Collection/S52-2-262.pdf 

Oh, patents! Asscher diamond cut

Copyright © Françoise Herrmann

Diamonds are forever...!  So are the cuts.

Joseph Asscher's diamond cut was patented in the 1903 French patent, FR324092, titled Nouveau mode de taille de diamants. To date, Asscher’s diamond cut is still in use. It is regarded as one of the cuts that gives the most brilliance to diamonds.

Joseph Asscher was a Dutch diamond cutter, operating out of the Asscher Diamond Company, founded by his father in 1854, in Amsterdam, The Netherlands.

Joseph Asscher famously cleaved the two largest diamonds ever found in South Africa: the Excelsior diamond found in 1893, weighing 970 carats (approx. 195 g),  and the Cullinan diamond, found in 1905, weighing 3,106.75 carats (aprox. 624 g). The Excelsior diamond was cleaved into ten stones weighing 13 to 68 carats.  The Cullinan diamond was cleaved into 105 stones of various cuts. The rough Cullinan diamond was gifted to the British monarch, King Edward VII, in 1907, who selected the Asscher Diamond Company in Amsterdam to cleave it. The largest cut Cullinan diamonds adorn the British Royal scepter and crown.

The four patent figure drawings showing the Asscher diamond cut are included. The drawings show the trapeze-shaped facets (c) and (d) of the diamond, with edges strictly parallel to the edges of the crown (a). The description of the inventive cut suggests 3 facets (c) for the upper portion or crown of the diamond, and 7 to 8 facets (d) for the lower portion or pavilion. The scope of the invention explicitly extends this sort cut to diamonds of varying shapes (rectangular, round or square).

The Asscher family, and entire company staff of 500 diamond polishers, were deported during World War II. The Asscher Diamond Company, was rebuilt in 1946. The Royal title was granted to the company in 1980 by the Dutch monarch. The Royal Asscher Company is headquartered in the original Asscher diamond factory building in Amsterdam, The Netherlands.   

References

Royal Asscher Company

http://www.royalasscher.com/