Multi-excitation fluorescence imaging for identifying clarity enhancement in gemstones

Tsung-Han Tsai

doi:10.1117/12.2592939

7 September 2021 Multi-excitation fluorescence imaging for identifying clarity enhancement in gemstones

Tsung-Han Tsai

Proceedings Volume 11815, Novel Optical Systems, Methods, and Applications XXIV; 1181505 (2021) https://doi.org/10.1117/12.2592939
Event: SPIE Optical Engineering + Applications, 2021, San Diego, California, United States

Abstract

Clarity enhancement is a common treatment method to improve the appearance of gemstones. Classifying the level of enhancement is an important task to gemological laboratories since it is associate with gemstone’s value. Current visual observation based evaluation requires considerable time and experience to identify the filling materials consistently. It is also unable to record the distribution, nor to quantify the visual influence of fracture filling. To improve the quality of identification, we demonstrate a treatment detection technique based on multi-excitation fluorescence imaging. The system is designed to reveal the filling materials while mitigate the background fluorescence from the mineral. Proper excitation wavelengths were selected based on preliminary spectroscopy and imaging studies. The experimental prototype used multiple light emitting diodes as the light sources; and adapted color camera combined with filters to monitor the fluorescence image of treated gemstones. This research utilized emerald treatment detection for demonstration. The system can reveal popular fillers in emerald such as oil, resin, and mixture of chemical compounds, and demonstrates rapid detection of clarity enhancement in emeralds.

Conference Presentation

Citation Download Citation

Tsung-Han Tsai "Multi-excitation fluorescence imaging for identifying clarity enhancement in gemstones", Proc. SPIE 11815, Novel Optical Systems, Methods, and Applications XXIV, 1181505 (7 September 2021); https://doi.org/10.1117/12.2592939

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