NON-INVASIVE GRADING TECHNIQUE FOR RUBY GEMSTONE USING CHARGE-COUPLED DEVICE (CCD)
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-02-28 |
| Journal | ASEAN Engineering Journal |
| Authors | Fatinah Mohd Rahalim, Juliza Jamaludin, Syarfa Najihah Raisin |
| Institutions | Universiti Sains Islam Malaysia |
| Citations | 1 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research proposes a reliable, non-invasive technique for grading the clarity characteristic of ruby gemstones using a Charge-Coupled Device (CCD) linear sensor system.
- Core Value Proposition: Replaces subjective, error-prone human visual assessment in ruby grading with a standardized, quantitative measurement system.
- Technology: Utilizes a CCD linear sensor paired with a low-power laser to analyze the light distribution characteristics (reflection and attenuation) through the ruby.
- Non-Invasive Advantage: The method does not disturb the internal physical or chemical composition of the gemstone, preserving its integrity.
- Quantitative Output: The system converts light intensity (lx) passing through the ruby into a measurable voltage value (V), which directly correlates to clarity.
- Key Achievement: The system demonstrated a high relative accuracy of 80% in validating the light distribution characteristic of the ruby.
- Validation: Statistical analysis (2-sample t-test using Minitab) confirmed a significant difference between the mean CCD voltage outputs when the ruby was present versus absent.
- Result Match: The experimental CCD output voltage (1.7918 V) closely matched the theoretical modeled voltage (1.9941 V).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| System Relative Accuracy | 80 | % | Reliability in detecting light intensity changes. |
| Experimental CCD Output (Ruby Present, Laser ON) | 1.7918 | V | Measured voltage used for clarity evaluation. |
| Theoretical CCD Output (Modeled) | 1.9941 | V | Calculated value based on light attenuation and reflection. |
| Reference CCD Output (Laser ON, No Ruby) | 1.583 | V | Baseline voltage corresponding to 1 lx intensity. |
| Reference CCD Output (Laser OFF, No Ruby) | 4.282 | V | Baseline voltage corresponding to 0 lx intensity (dark condition). |
| CCD Voltage vs. Light Intensity Gradient | -2.6983 | V/lx | Inverse proportional relationship (V = -2.6983I + 4.2817). |
| Optimum Laser Intensity | 0.5 | lx | Required for efficient CCD linear sensor operation. |
| Optimum Operating Temperature | 25-33 | °C | Required range for CCD linear sensor stability. |
| Optimum Relative Humidity | 65-85 | % | Required range for CCD linear sensor stability. |
Key Methodologies
Section titled âKey MethodologiesâThe experiment was designed to measure the light intensity received by the CCD linear sensor after passing through the ruby, focusing on optimal operating conditions.
- Environmental Setup: The system was housed in a dark area to ensure the CCD received the highest intensity of light solely from the laser source.
- Sensor Optimization: Operating conditions for the CCD linear sensor were strictly maintained: temperature between 25-33 °C, relative humidity between 65-85%, and laser intensity at 0.5 lx to prevent sensor saturation.
- Hardware Integration: The system utilized a low-power laser, the ruby sample, a CCD linear sensor, and an Arduino Uno Microcontroller for system control and data acquisition, with results displayed on an oscilloscope.
- Theoretical Modeling (LabVIEW): Mathematical models were developed to predict the final light intensity ($I_{final}$) and voltage output, accounting for two primary phenomena:
- Light Reflectance: Modeled using Fresnel equations based on the refractive indices of air ($n_1$) and ruby ($n_2$).
- Light Attenuation: Modeled using the Beer-Lambert Law ($I_{out} = I_{in}e^{-ax}$), where light is absorbed or scattered within the ruby.
- Data Collection: A total of 600 data points were collected for each experimental condition (Laser ON/OFF, with/without ruby).
- Statistical Validation (Minitab): A 2-sample t-test was performed to compare the mean CCD voltage output values, confirming that the presence of the ruby caused a statistically significant change in light intensity.
- Accuracy Calculation: The systemâs reliability was determined by calculating the relative accuracy between the theoretical voltage (1.9941 V) and the experimental voltage (1.7918 V).
Commercial Applications
Section titled âCommercial ApplicationsâThis non-invasive CCD-based grading technique offers significant advantages for industries requiring objective assessment of transparent materials.
- Gemstone Grading and Certification: Provides a standardized, quantitative metric for assessing the clarity of rubies and other colored stones (graded by 4Cs), reducing subjectivity in the high-value diamond trade system.
- Quality Control in Synthetic Gem Manufacturing: Enables rapid, non-destructive inspection of laboratory-grown rubies to ensure quality and detect internal defects (e.g., inclusions or variations in chromium/iron content).
- Non-Destructive Testing (NDT): The methodology is transferable to NDT applications for transparent or semi-transparent materials, such as specialized optical components, lenses, and crystal structures, where internal clarity is paramount.
- Optoelectronics and Sensor Technology: Utilizes the CCD linear sensorâs high sensitivity and reliability in optical systems, applicable to precision machinery, laser alignment, and high-resolution scanning devices.
- Forensic and Authentication Services: Offers objective data to support the authentication of gemstones, helping to distinguish natural stones from imitations or enhanced treatments by quantifying light transmission characteristics.
View Original Abstract
Ruby is one of the most popular and high-value gemstones that always attract the gemologist and jeweler in the diamond market. The wide use of ruby in various industries makes the grading of this gems more complicated due to a lot of synthetic and imitation rubies are made. The current grading techniques are mostly depending on the human visual assessment which prone to errors. This paper proposes a system that helps in grading the clarity characteristic of the ruby in non-invasive manner. The system includes a charge-coupled devices (CCD) and laser that is designed in the most suitable and effective way to conduct inspection on the light intensity of the ruby which will then determine the clarity of the ruby. CCD linear sensor is widely known as the reliable sensor especially when use in the optical system. The CCD linear sensor capture the light intensity from the ruby and convert it into the voltage value. The result shows a value of 1.7918 V obtained from the CCD linear sensor when ruby is placed in the system. This concludes that the CCD system can detect even slightest changes in the light intensity that can pass through the ruby and falls on the CCD linear sensor. The system is proven to be a reliable and effective system with 80% accuracy.