| SHAO Hui-ping,YAN Xue-jun,YAN Jun,WANG Jin,YU Si-yi,PENG Qiu-jin,HU Xian-chao.Identification of Two Kinds of Seawater Cultured Gray Pearls by Fourier Transform Infrared Spectroscopy and Ultraviolet-visible Absorption Spectroscopy[J].Rock and Mineral Analysis,2019,38(5):489-496 |
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| Identification of Two Kinds of Seawater Cultured Gray Pearls by Fourier Transform Infrared Spectroscopy and Ultraviolet-visible Absorption Spectroscopy |
| Received:September 28, 2018 Revised:March 14, 2019 |
| DOI：10.15898/j.cnki.11-2131/td.201809280109 |
| Key words: gray pearl ultraviolet-visible absorption spectroscopy structure nacreous layer nucleus irradiation treatment |
| Author Name | Affiliation | E-mail | | SHAO Hui-ping | Zhejiang Fangyuan Test Group Co., LTD, Hangzhou 310013, China
Research Center of Analysis and Measurement, Zhejiang University of Technology, Hangzhou 310014, China | | | YAN Xue-jun | Zhejiang Fangyuan Test Group Co., LTD, Hangzhou 310013, China | | | YAN Jun | Zhejiang Fangyuan Test Group Co., LTD, Hangzhou 310013, China | | | WANG Jin | Wenzhou Institute of Science and Technology, Zhejiang University of Technology, Wenzhou 325024, China | | | YU Si-yi | Zhejiang Fangyuan Test Group Co., LTD, Hangzhou 310013, China | | | PENG Qiu-jin | Zhejiang Fangyuan Test Group Co., LTD, Hangzhou 310013, China | | | HU Xian-chao | Research Center of Analysis and Measurement, Zhejiang University of Technology, Hangzhou 310014, China | huxc@zjut.edu.com |
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| Abstract: |
BACKGROUND:Akoya pearl is a biomineralized organic gemstone. The mineral composition and microtextural analysis, and the identification method of color formation of this type of pearl are still lacking.
OBJECTIVES:To identify natural gray pearls from treated-color gray pearls.
METHODS:The spectroscopic and textural characteristics of two kinds of seawater cultured gray pearls with white or gray nucleus were comparatively investigated by optical microscope, Fourier transform infrared spectroscopy, ultraviolet-visible absorption spectroscopy, and energy dispersive X-ray fluorescence spectrometry.
RESULTS:The gray pearls with white or gray nucleus had diameters from 5mm to 9mm, the thickness of 300-500μm. The nacreous layer and its corresponding nucleus of the two kinds of gray pearls were composed mainly of biological aragonite, and their corresponding nacreous layers were rich in Sr and poor in Mn. The pearl with the gray nucleus was rich in Mn. The valence state of Mn was increased due to irradiation, resulting in gray of the pearl core and the whole pearl. In general, the pearls with a white nucleus had an obvious reflection band from 300nm to 400nm in the ultraviolet-visible absorption spectra. On the contrary, those pearls with a light or heavy gray nucleus had a reflection band from 400nm to 500nm.
CONCLUSIONS:The two types of gray pearls are all marine cultured pearls. The difference of ultraviolet absorption spectra of the two types of pearls can be used as a basis for judging whether the gray pearls are irradiatedly colored. |
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