Identification of "Chocolate Pearls" Treated by Ballerina Pearl Co.

Wang, Wuyi; Scarratt, Kenneth; Hyatt, Akira; Shen, Andy H.; Hall, Matthew

doi:10.5741/gems.42.4.222

Cited by 19 publications

(9 citation statements)

References 6 publications

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“…I rradiation, dyeing, bleaching, and heat treatment are widely used methods to alter pearl color. Although most artificial colors are easily recognized, some resemble attractive colors that occur in nature Li and Chen, 2001;Zachovay, 2005;Wang et al, 2006;"Better techniques improve brown pearls," 2006;McClure et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

Natural Pearls from Australian <i>Pinctada Maxima</i>

Scarratt¹,

Bracher²,

Bracher³

et al. 2012

Gems & Gemology

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Section: Discussionmentioning

confidence: 99%

Natural Pearls from Australian <i>Pinctada Maxima</i>

Scarratt¹,

Bracher²,

Bracher³

et al. 2012

Gems & Gemology

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“…Our study suggested that both color treatment and optical brightening have been applied to fancycolor freshwater Edison pearls, and their identification can be achieved by a combination of conventional gemological methods (microscopic observation and long-wave fluorescence observation) and advanced instrumental techniques (Raman spectroscopy, trace element analyses, and long-wave and short-wave UV fluorescence spectroscopy). It is worth noting that conventional UV-Vis reflectance spectroscopy is a very effective method to identify color treatment in golden or dark-colored saltwater pearls (Elen, 2001;Wang et al, 2006;Karampelas et al, 2011;Zhou et al, 2012Zhou et al, , 2016. However, the identification of color treatment in freshwater pearls using UV-Vis reflectance spectroscopy is more challenging and less effective in our experience with these samples (results not shown).…”

Section: Discussionmentioning

confidence: 83%

“…Detection of color treatment is an important part of pearl identification in gemological laboratories, both for saltwater and freshwater pearls (Elen, 2001;Wang et al, 2006;Karampelas et al, 2007Karampelas et al, , 2011Zhou et al, 2012Zhou et al, , 2016Tsai and Zhou, 2020). Freshwater cultured pearls, in particular, can exhibit a Figure 1.…”

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confidence: 99%

Detection of Color Treatment and Optical Brightening in Chinese Freshwater "Edison" Pearls

Zhou¹,

Ho²,

Shih³

et al. 2021

G&G

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Color origin is an important part of pearl identification for gemological laboratories. Freshwater cultured pearls can exhibit a wide range of colors, which can be either naturally formed or artificially modified by post-harvest treatments. The most common color treatments are dyeing and irradiation. In this project, a group of 23 freshwater "Edison" pearls (a trade name referring to near-round to round freshwater bead cultured pearls invented and produced by Zhejiang Grace Pearl Jewellery Co Ltd in China), reportedly with a mix of natural and treated colors, were analyzed using various gemological and advanced instrumental techniques in order to distinguish their color origin. A number of techniques, including microscopic observation, long-wave UV fluorescence observation, long-wave and short-wave fluorescence spectroscopy, Raman spectroscopy, and trace element analyses, were used in this study. Of the 23 freshwater samples, 19 have been confirmed as bead cultured pearls and 4 have been identified as non-bead cultured pearls. In addition, seven samples have been identified as colortreated, while five of the remaining 16 samples were also identified as being optically brightened (a process commonly used on freshwater cultured pearls to improve appearance factors such as luster). Our results proved that color treatment in these freshwater pearls could be confidently identified using this combination of techniques, as could optical brightening processes that are routinely applied to untreated, naturally colored freshwater cultured pearls post-harvest.

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“…Pearls are mainly composed of calcium carbonate (CaCO 3 ) biominerals together with organic matrix and water. In pearl analysis, Raman spectroscopy is a rapid, non-destructive technique that mainly is used to identify different CaCO 3 polymorphs, including aragonite, calcite, and vaterite, and determine color origin of the pearl: whether it is caused by natural pigments (in particular, polyenes and uroporphyrin) or has been modified by treatment processes [5,[59][60][61].…”

Section: Raman Mapping Of Pearlsmentioning

confidence: 99%

Raman and Photoluminescence Mapping of Gem Materials

et al. 2021

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Raman and photoluminescence (PL) mapping is a non-destructive method which allows gemologists and scientists to evaluate the spatial distributions of defects within a gem; it can also provide a method to quickly distinguish different species within a composite gem. This article provides a summary of this relatively new technology and its instrumentation. Additionally, we provide a compilation of new data for various applications on several gemstones. Spatial differences within diamonds can be explored using PL mapping, such as radiation stains observed on the rough surface of natural green diamonds. Raman mapping has proven useful in distinguishing between omphacite and jadeite within a composite of these two minerals, identifying various tourmaline species within a heterogeneous mixture, and determining the calcium carbonate polymorphs in pearls. Additionally, it has potential to be useful for country-of-origin determination in blue sapphires and micro-inclusion analysis. As new avenues of research are explored, more applications for gem materials will inevitably be discovered.

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Identification of "Chocolate Pearls" Treated by Ballerina Pearl Co.

Cited by 19 publications

References 6 publications

Natural Pearls from Australian <i>Pinctada Maxima</i>

Natural Pearls from Australian <i>Pinctada Maxima</i>

Detection of Color Treatment and Optical Brightening in Chinese Freshwater "Edison" Pearls

Raman and Photoluminescence Mapping of Gem Materials

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