Optical Whitening and Brightening of Pearls: A Fluorescence Spectroscopy Study

Zhoi, Chunhui; Tsai, Tsung-Han; Sturman, Nicholas; Nilpetploy, Nanthaporn; Manustrong, Areeya; Lawanwong, Kwanreun

doi:10.5741/gems.56.2.258

Cited by 6 publications

(1 citation statement)

References 8 publications

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“…It magnifies the contrast between the signal and background and completely filters out the excitation light source without blocking the fluorescence emitted by the sample, which makes weak fluorescence clearly visible [9]. For example, the use of fluorescence spectroscopy can effectively distinguish whether pearls have been brightened [10] or dyed [11], and can also provide evidence regarding the origin of amber [12].…”

Section: Three-dimensional Fluorescence Spectroscopy Featuresmentioning

confidence: 99%

Identification of Heat-Treated Sapphires from Sri Lanka: Evidence from Three-Dimensional Fluorescence Spectroscopy

Zhang

Chen

2022

Crystals

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Heat treatment is an important method used to improve the value of sapphires. The identification of heat-treated sapphires is a significant and challenging subject in gemology. In this study, natural sapphire samples from Ratnapura, Sri Lanka, were heated at different temperatures from 900 °C to 1500 °C. Then, the samples were examined by FTIR and three-dimensional fluorescence spectrometry. When excited by 450 nm light, most natural samples emitted a fluorescence band between 540 nm and 560 nm. This fluorescence disappeared after low-temperature heat treatment. Therefore, the presence of fluorescence between 540 nm and 560 nm is evidence of unheated sapphires from Sri Lanka. Almost all of the samples emitted fluorescence centered at 470 nm after high-temperature treatment. Therefore, fluorescence at 470 nm indicates that the sapphires from Sri Lanka were treated at a high temperature. Three-dimensional fluorescence spectroscopy can serve as a method to identify heat-treated sapphires.

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Section: Three-dimensional Fluorescence Spectroscopy Featuresmentioning

confidence: 99%