Provenance determination of sapphires and rubies using laser-induced breakdown spectroscopy and multivariate analysis

Abstract

Determination of gem provenance is a topic of research in the gemological community for financial, security, and societal reasons. Laser-induced breakdown spectroscopy (LIBS) and multivariate analysis have the potential to revolutionize the field of gem provenance. This study acquired LIBS spectra from 569 rough sapphire and ruby specimens from 21 localities in 11 countries. The spectra were analyzed using the multivariate technique partial least-squares regression (PLSR) in separate algorithms for sapphires and rubies. Each algorithm consists of a series of PLS models. Each model compares the spectra from a locality of interest to the spectra from all other localities in the database. Success rates, as determined by the percent of correct provenance identifications, are 98.9% (sapphire) and 96.0% (ruby) for country of origin and 97.9% (sapphire) and 95.4% (ruby) for deposit of origin. Individual deposits are not recognized by the concentrations of a few elements; rather, the unique compositional signature of each deposit consists of the ratios of many elements, primarily Ca, Zr, Fe, Ba, Mt, Ti, Sr, Si, Cr, H, C, and Li, some of which may reside in inclusions. This work demonstrates that determination of country or deposit of origin may be related to a quantitative measure with a high level of success.

Diversity in Ruby Geochemistry and Its Inclusions: Intra- and Inter- Continental Comparisons from Myanmar and Eastern Australia

“…A plethora of detailed data now exists on ruby characteristics available from many global sites, as exploration, mining and gem researchers, gem institutions and trade laboratories continue to openup studies on this valuable gemstone [2,[81][82][83]. This, with improved techniques of characterizing ruby through analytical advances [84], and more sophisticated statistical methods of identifying links/differences in analytical data from known sources [85][86][87][88], will enlighten future studies. Detailed mineral assemblage studies and P-T conditions of their formation within ruby-host lithology will become further refined to use as potential exploration vectors for new ruby deposits [5].…”

Cause analysis of chatoyancy of sapphires from Shandong, China

“…3 As a gemstone, sapphire is one of the most valuable gemstones and is produced in many countries worldwide, for example, Myanmar, Thailand, Sri Lanka, Australia, etc. [4][5][6][7] The sapphire ores in the Shandong province are the largest reserves and have the best quality in China; it is located in the western part of the Tan-Lu fault zone, southeast of the North China Craton. 8 To the best of our knowledge, the gemological properties, mineralogical properties, chromogenic mechanism, color modication and inclusion study of Shandong sapphires have been investigated systematically and thoroughly.…”

Crystal Chemical Characterisation of Red Beryl by ‘Standardless’ Laser‐Induced Breakdown Spectroscopy and Single‐Crystal Refinement by X‐Ray Diffraction: An Example of Validation of an Innovative Method for the Chemical Analysis of Minerals

“…In the last decades, LIBS has been widely employed in several research fields: for example, archaeometry, metallurgy, geochemistry and environment (Harmon et al 2006, Giakoumaki et al 2007, Hanh and Omenetto 2012, Noll 2012, Blagoev et al 2013. The advantages of this method have been also utilised in geology (Vadillo and Laserna 1996, Senesi 2014, Fabre 2020, to characterise meteorites (Dell'Aglio et al 2010, Senesi et al 2016 and, lastly, to study minerals (McMillan et al 2006, Rossi et al 2014, Khajehzadeh and Kauppinen 2015, Kochelek et al 2015, McManus et al 2018.…”