A Review of Analytical Methods Used in Geographic Origin Determination of Gemstones

Groat, Lee A.; Giuliani, Gaston; Stone-Sundberg, Jennifer; Sun, Ziyin; Renfro, Nathan D.; Palke, Aaron C.

doi:10.5741/gems.55.4.512

Cited by 28 publications

(27 citation statements)

References 49 publications

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“…Fourier-transform infrared spectroscopy (FTIR) is performed on every alexandrite to distinguish natural from synthetic material (Stockton and Kane, 1988) and to identify imitations. Natural alexandrites are then sent for laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS); see Groat et al (2019), pp. 512-535 of this issue.…”

Section: Methodsmentioning

confidence: 99%

Geographic Origin Determination of Alexandrite

Sun¹,

Palke²,

Muyal³

et al. 2019

G&G

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A fter the discovery of a gem mineral with unusual color-change behavior in the Russian Ural Mountains during the early 1830s, Swedish mineralogist Nils Adolf Erik Nordenskiöld named this new gem alexandrite in 1834 in honor of the future Czar Alexander II (Kozlov, 2005). This immediately created a royal and romantic aura around this variety of chrysoberyl. The most coveted alexandrites exhibit a lush green to greenish blue color in daylight and a warm, bright red shade in candlelight (Levine, 2008); some fine Brazilian and Indian alexandrite examples are shown in figures 1-3 and 6. This phenomenal color change is caused by the presence of trace Cr 3+ substituting for Al 3+ in the chrysoberyl crystal structure. Alexandrite is routinely described as "emerald by day, ruby by night." It is a stone of duality-green or red, cool or warm, day or night (Levine, 2008). Because of its rare and attractive color-change phenomenon, alexandrite has been highly sought after and is one of the most valuable gemstones in the trade. Alexandrite, particularly fine-quality material, is also very scarce; it has generally been a byproduct of mining other major colored stones. Overall production statistics are hard to evaluate. It has been mined

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Section: Methodsmentioning

confidence: 99%

Geographic Origin Determination of Alexandrite

Sun¹,

Palke²,

Muyal³

et al. 2019

G&G

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Section: Colored Gemstonesmentioning

confidence: 99%

“…The origin of high-value colored gemstones is of increasing importance for jewelry trade, as the origin of a gemstone can be considered as a value-determining factor and may influence the salability of a stone [48]. Analytical methods used in geographic origin determination of gemstones were reviewed by Groat et al [48]. Various parameters starting from basic physical properties like refractive index and specific gravity over the characteristics of inclusions and spectroscopic characteristics up to trace element chemistry and isotope ratios were monitored.…”

Section: Colored Gemstonesmentioning

confidence: 99%

Analytical Proof of Origin for Raw Materials

2021

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Growing public interest in getting information on the origin of raw materials used to manufacture goods for daily life has triggered the development of concepts to increase the transparency of raw material supply chains. Analytical proofs of origin (APOs) for raw materials may support those transparency concepts by giving evidence about the origin of a specific raw material shipment. For a variety of raw materials like gemstones, TTT (tantalum, tin, tungsten) minerals, and others, APOs have been developed. The identification of features that distinguish different origins, databases of those features from reliable reference samples, and a data evaluation strategy adopted to the envisaged application scenario are the key aspects of APO methods. Here, an overview is given on APO methods developed for different raw materials and application cases.

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“…PL spectroscopy can detect these features even at concentrations lower than 10 ppb [3]. Raman spectroscopy has proven vital for a host of other gemstones as well to aid in their identification [4][5][6][7].…”

Section: Introductionmentioning

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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A Review of Analytical Methods Used in Geographic Origin Determination of Gemstones

Abstract: crystallizes in the 3-2/m class of the trigonal system (space group R3 c) with hexagonal unit cell axes of a ≈ 4.76 Å and c ≈ 12.99 Å (Cesbron et al., 2002). This uniaxial negative material (n ω =

Cited by 28 publications

References 49 publications

Geographic Origin Determination of Alexandrite

Geographic Origin Determination of Alexandrite

Analytical Proof of Origin for Raw Materials

Raman and Photoluminescence Mapping of Gem Materials

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