Polynesian Black Pearls

Goebel, Marisa; Dirlam, Dona M.

doi:10.5741/gems.25.3.130

Cited by 15 publications

(27 citation statements)

References 6 publications

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“…As expected, no evidence for calcite (i.e., 711 cm −1 peak) was observed in the Raman spectra of the natural-color, "chocolate" treated, or dyed Tahitian cultured pearls. Other Raman features are attributed to various types of organic components, such as conchiolin and porphyrin (Goebel and Dirlam, 1989;Liu, 2003;Huang, 2006). The intensities of these organic component bands varied significantly among the NCTCPs, but they clearly increased with the tone of the cultured pearl colors (not shown in figure 13).…”

Section: Discussionmentioning

confidence: 99%

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

Wang¹,

Scarratt²,

Hyatt³

et al. 2006

Gems & Gemology

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Section: Discussionmentioning

confidence: 99%

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

Wang¹,

Scarratt²,

Hyatt³

et al. 2006

Gems & Gemology

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“…The most significant difference in the reflectance spectra of P. sterna and P. margaritifera is the absence of the 700 nm absorption feature for P. sterna. This absorption is characteristic of P. margaritifera (figure 15; see also Goebel and Dirlam, 1989;Iwahashi and Akamatsu, 1994;and Elen, 2002).…”

Section: Separation Frommentioning

confidence: 82%

Cultured Pearls from the Gulf of California, Mexico

Kiefert¹,

Moreno²,

Arizmendi³

et al. 2004

Gems & Gemology

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Black pearls have been found in Mexico's Gulf of California since the area was settled more than 2,000 years ago. Attempts at culturing pearls in this area have met with varying success over the past century. Today, a pearl farm in Guaymas is producing commercial quantities of mabe as well as bead-nucleated full-round cultured pearls from the indigenous pearl oyster Pteria sterna. This article provides an overview of the history of natural and cultured pearls from Mexico, describes pearl culturing at the Guaymas farm, and focuses on the properties of bead-nucleated cultured pearls from P. sterna. These cultured pearls have a brown or gray to dark gray bodycolor with various interference colors caused by the stacking of platy aragonite crystals and organic matter. One indication of their natural color (and their Mexican provenance) is a red fluorescence to long-wave UV radiation.

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“…EDXRF is also used to detect treatments used on natural and cultured pearls to improve their colour-with inorganic substances such as silver, iodine, bromine etc. [10,11].…”

Section: Introductionmentioning

confidence: 99%

Chemical Characteristics of Freshwater and Saltwater Natural and Cultured Pearls from Different Bivalves

Karampelas¹,

Mohamed²,

Abdulla³

et al. 2019

Minerals

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The present study applied Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) on a large number of natural and cultured pearls from saltwater and freshwater environments, which revealed that freshwater (natural and cultured) pearls contain relatively higher quantities of manganese (Mn) and barium (Ba) and lower sodium (Na), magnesium (Mg) and strontium (Sr) than saltwater (natural and cultured) pearls. A few correlations between the host animal’s species and chemical elements were found; some samples from Pinctada maxima (P. maxima) are the only studied saltwater samples with 55Mn >20 ppmw, while some P. radiata are the only studied saltwater samples with 24Mg <65 ppmw and some of the P. imbricata are the only studied saltwater samples with 137Ba >4.5 ppmw. X-ray luminescence reactions of the studied samples has confirmed a correlation between its yellow-green intensity and manganese content in aragonite, where the higher Mn2+ content, the more intense the yellow-green luminescence becomes. Luminescence intensity in some cases is lower even if manganese increases, either because of pigments or because of manganese self-quenching. X-ray luminescence can be applied in most cases to separate saltwater from freshwater samples; only samples with low manganese content (55Mn <50 ppmw) might be challenging to identify. One of the studied natural freshwater pearls contained vaterite sections which react by turning orange under X-ray due to a different coordination of Mn2+ in vaterite than that in aragonite.

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Polynesian Black Pearls

Cited by 15 publications

References 6 publications

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

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

Cultured Pearls from the Gulf of California, Mexico

Chemical Characteristics of Freshwater and Saltwater Natural and Cultured Pearls from Different Bivalves

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