Gemstone Facet Angles for Watch Dial Light Dispersion

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Solution Overview

Problem

Gemstones, especially diamonds, used in wristwatches experience suboptimal dispersion and sparkle due to their small size, leading to a diffuse glow rather than distinct flashes of light, and the octagonal cut results in light loss and visual disruption when integrated into watch dials.

Innovation Solution

A gemstone design with specific angular arrangements, including a crown with 35° upper part angle and 40.5° lower part angle, optimized to guide light effectively and enhance dispersion, along with a reduced number of facets and angular planes, to maintain high light output and sparkle even at small sizes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a gemstone with full number of facets (56 facets plus table) is used, then dispersion and sparkle are enhanced, but the individual flashes of light become too small to be perceived by the human eye when the gemstone is small in size

Engineering Contradiction:
Improvedispersion and sparkleVSAvoidperceptibility of individual flashes of light
Core Design Contradiction:
Illumination intensityVSDifficulty of detecting and measuring

Solution Approach 1:

The invention divides the crown facets into two distinct groups: first crown facets with a first angle range (34-36 degrees) and second crown facets with a second angle range (40-42 degrees). This segmentation allows different facets to serve different optical functions - some facets create larger, more perceptible flashes of light while others contribute to dispersion, resolving the contradiction between enhanced sparkle and perceptibility.

Inventive Principle:
Principle #1Segmentation

2Difficulty of detecting and measuring

If an octagonal cut with only sixteen facets is used, then the individual facets remain above the individual perceptual size, but light is lost at each corner where facets face each other at certain angles

Engineering Contradiction:
Improveperceptibility of individual flashes of lightVSAvoidlight loss
Core Design Contradiction:
Difficulty of detecting and measuringVSLoss of energy

Solution Approach 1:

The invention changes the angular parameters of the crown facets by introducing two distinct angle ranges (34-36 degrees and 40-42 degrees) instead of using uniform angles. This parameter variation optimizes light reflection paths to prevent light loss at corners while maintaining facet sizes that are perceptible to the human eye, thereby resolving the contradiction between perceptibility and light efficiency.

Inventive Principle:
Principle #35Parameter changes

3Difficulty of detecting and measuring

If an octagonal cut with sixteen facets is used, then individual facets are perceptible, but the unified rhythm of facet arrangement visually clashes with other design elements of the watch

Engineering Contradiction:
Improveperceptibility of individual flashes of lightVSAvoidcompatibility with watch design elements
Core Design Contradiction:
Difficulty of detecting and measuringVSAdaptability or versatility

Solution Approach 1:

The invention applies different angular characteristics to different groups of crown facets - first crown facets have angles of 34-36 degrees while second crown facets have angles of 40-42 degrees. This local differentiation in facet properties creates visual variety and rhythm that can harmonize with different watch design elements, resolving the contradiction between perceptibility and design compatibility.

Inventive Principle:
Principle #3Local quality

4Difficulty of detecting and measuring

If the number of crown facets is reduced to achieve larger individual flashes of light, then perceptibility improves, but the overall light yield and dispersion may be compromised

Engineering Contradiction:
Improveperceptibility of individual flashes of lightVSAvoidoverall light yield and dispersion
Core Design Contradiction:
Difficulty of detecting and measuringVSIllumination intensity

Solution Approach 1:

The invention segments the crown facets into two functional groups with different angles, where first crown facets (34-36 degrees) and second crown facets (40-42 degrees) work together to both create perceptible flashes of light and maintain overall light yield. This segmentation allows the gemstone to achieve both perceptibility and optical performance simultaneously.

Inventive Principle:
Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design ensures optimal light yield and high dispersion, making the gemstone appear more vibrant and interesting by dominating the original color perception with spectral colors, and maintaining a clear, aesthetically pleasing light pattern under various viewing angles, including flat positions.

Implementation Method 1

Dispersion is the breakdown of white light into its spectral colors. In other words, the term dispersion means the different refraction according to the different refractive indices of the different wavelengths of light.

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

Total reflection occurs when a ray of light falls below the angle of total reflection attempting to exit from an optically denser medium into an optically thinner medium. If the light ray strikes the boundary of the two optical media within the angle of total reflection, it is 'totally' reflected.

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3537919B1Gemstone
Publication Date: 2022.04.27 REALIZATION DESAL AG
  • EP3537919B1 patent drawingFigure 1(a)~1(d)
  • EP3537919B1 patent drawingFigure 2(a)~2(d)
  • EP3537919B1 patent drawingFigure 3(a)~3(e)

AI summary

The invention relates to a gemstone (1) comprising: a crown (2) having a plurality of crown facets (11, 12) and a table (10); a girdle (3); and a pavilion (4) having a plurality of pavilion facets (13, 14). A crown angle (α) is between 34.5° and 35.5°, preferably 35°, and a pavilion angle (β) is between 40° and 41°, preferably between 40.2° and 40.8°, particularly preferably 40.5°.