Abstract

RUIZ, Valentina González; TOLOZA, Javier García; BASTIDAS, Jesús Alberto Ágreda  and  SERNA, Elianna Castillo. Evaluation of emeralds by their origin: Multivariate analysis - Infrared spectra. Rev.Colomb.Quim. [online]. 2021, vol.50, n.3, pp.24-31.  Epub July 20, 2022. ISSN 0120-2804.  https://doi.org/10.15446/rev.colomb.quirn.v50n3.98674.

Colombian emeralds, 26 from Palo Arañado (eastern emerald zone, Chivor district, Boyacá, Colombia), and 28 from Santo Domingo - La Pava mine (western emerald zone, Muzo district, Boyacá, Colombia), together with 30 from Kafubu - Zambia, were studied by reflectance Fourier transform infrared spectroscopy, principal component analysis, clustering, and partial least squares -discriminant analysis, in order to differentiate them by geographical origin. The spectra were smoothed and a baseline correction was made. The principal component analysis showed that the wavenumbers 2,474; 2,640; 2,686; 2,818; 5,448, and 6,815 cm-' are the most significant in the first principal component and the most valuable in separating the emeralds by their geographical origin. This allowed us to completely discriminate emeralds from Santo Domingo and Zambia, while only five emeralds from Palo Arañado were '00 % differentiable from the other two groups of emeralds.

Keywords : Emeralds; geographical origin; principal component analysis; clustering; partial least squares - discriminant analysis.

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