Dual-modal identification of jadeite based on optical coherence tomography images and Raman spectral features

Area of Science:

• Gemology
• Materials Science
• Analytical Chemistry

Background:

• Low-quality jadeite is often treated (bleaching, filling, dyeing) to enhance appearance and value.
• Distinguishing treated jadeite from natural jadeite is crucial for the gemstone market.

Purpose of the Study:

• To develop and validate a combined Raman spectroscopy and OCT approach for identifying treated jadeite.
• To characterize the spectral and textural signatures of natural, bleached/filled, and dyed jadeite.

Main Methods:

• Raman spectroscopy was used to identify characteristic peaks for jadeite composition and fillers.
• Optical coherence tomography (OCT) was employed to analyze the texture of jadeite samples.
• Image processing techniques were applied to extract texture vectors from OCT data.

Main Results:

• Specific Raman peaks (205, 377, 700, 1040 cm⁻¹) confirm jadeite composition.
• Epoxy filler presence detected via Raman peaks (1113, 1187, 1609 cm⁻¹), with 1113 and 1609 cm⁻¹ being significant.
• Dyed jadeite shows a fluorescence background in Raman spectra.
• OCT texture vectors differ between natural and treated jadeite, often showing lower intensity in treated samples due to processing damage.

Conclusions:

• Combined Raman spectroscopy and OCT effectively differentiate natural from treated jadeite.
• Spectral and textural analyses provide distinct markers for bleaching, filling, and dyeing.
• The methods offer a reliable approach for gemstone authentication and quality assessment.