Gemstone Color Grading with Daylight-Approximating Broadband Light
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Solution Overview
Problem
Existing technologies for automated diamond color grading fail to accurately replicate the visual perception of human gemologists under daylight-approximating conditions, leading to inconsistencies and inaccuracies in color grading.
Innovation Solution
A system that includes a rotatable enclosure with broadband visible light (BBV) and UV light sources, controlled by a programmable controller, which captures color-measurement images of a diamond from various angles to process and grade its color using advanced image processing and 3D volumetric modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional colorimetric systems with filtered light sources are used, then the system structure is relatively simple, but the lighting conditions do not accurately replicate daylight which is the standard for visual color analysis
Solution Approach 1:
The patent changes the spectral parameters of the light source by using a broadband visible light source (400-700nm) that approximates daylight conditions, replacing traditional filtered light sources. This parameter change enables accurate color grading that matches human visual perception under daylight, resolving the contradiction between illumination accuracy and system complexity.
Solution Approach 2:
The patent replaces mechanical optical filtering systems with a broadband light source combined with digital image processing. Instead of using physical filters to select wavelengths, the system uses a broadband source and processes the full spectrum through computational methods, reducing mechanical complexity while improving daylight approximation.
2Measurement precision
If spectrophotometers detecting full spectrum light are used, then comprehensive spectral data is obtained, but the systems fail to accurately replicate human visual perception for diamond color grading
Solution Approach 1:
The patent copies the human visual system's response characteristics by using an image sensor with spectral sensitivity matched to human photopic vision and by illuminating with daylight-approximating light. This creates a measurement system that replicates human visual perception rather than measuring physical spectral properties, achieving accurate color grading that matches gemologist evaluation.
Solution Approach 2:
The patent changes the measurement parameters from full spectral detection to visible range imaging (400-700nm) with specific illumination conditions that match daylight. This parameter change aligns the measurement system with human visual perception, enabling accurate color grading while simplifying the detection process compared to full spectrophotometry.
3Productivity
If automated color grading systems are implemented, then productivity increases, but the systems produce inconsistent and inaccurate color grades compared to human gemologist evaluation
Solution Approach 1:
The patent replaces traditional automated colorimetric measurement systems with an imaging-based system that captures photographs under controlled daylight-approximating conditions. This substitution uses digital image processing and color science algorithms to analyze the captured images, providing automated grading that consistently replicates human visual evaluation, thereby improving both productivity and reliability.
Solution Approach 2:
The system incorporates feedback through standardized illumination conditions, controlled camera exposure settings, and comparison against reference standards. The automated processing of captured images with calibrated color algorithms provides consistent, repeatable measurements that maintain reliability while increasing productivity compared to manual evaluation.
4Measurement precision
If multiple light sources and imaging angles are used, then measurement accuracy improves, but the device complexity and operation time increase
Solution Approach 1:
The patent performs preliminary actions by pre-configuring the illumination system with daylight-approximating broadband light sources and pre-calibrating the image sensor's spectral response to match human vision. The measurement protocol is pre-programmed with optimal exposure settings and analysis algorithms. This preliminary preparation enables rapid, accurate color grading without requiring multiple measurement iterations, reducing measurement time while maintaining precision.
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 system achieves accurate and consistent diamond color grading by simulating daylight conditions and utilizing advanced imaging techniques, thereby improving the reliability and precision of automated diamond color evaluation.
Implementation Method 1
one or more sources of broadband visible light (BBV), the sources of BBV light being controllable by a programmable controller
Implementation Method 2
one or more sources of UV light are mounted on the actuator in the vicinity of the image sensor
Implementation Method 3
an image sensor for capturing a plurality of color-measurement images of the mounted gemstone
Data Source
Figure 1A
Figure 1B~1D
Figure 2A
AI summary
A system for the automatic grading of a cut/polished gemstone (SUT) includes an enclosure with a stage for mounting the cut/polished SUT. The enclosure further includes one or more sources of broadband visible (BBV) light, the sources of BBV light being controllable by a programmable controller; an image sensor for capturing a plurality of images of a mounted SUT, and one or more sources of UV light mounted within the enclosure. The controller captures images of the mounted SUT from one or more selected angles relative to the sensor elevation axis and relative to the position of the SUT on the stage rotation axis; an image capturing module is configured for processing the one or more images; and, a light grade calculation module is configured for grading the cut/polished SUT using light indicative parameters from at least a part of the one or more images captured.