Investigation of Geuda Gemstones, before and after the Heat Treatment using FTIR Spectroscopy

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dc.contributor.authorRamesh, T.G.
dc.contributor.authorJaliya, R.G.C.
dc.contributor.authorIllangasinghe, I.K.M.S.C.K.
dc.contributor.authorDiyabalanage, S.
dc.contributor.authorJayasinghe, N.
dc.contributor.authorDharmaratne, T.S.
dc.date.accessioned2021-02-25T06:27:33Z
dc.date.available2021-02-25T06:27:33Z
dc.date.issued2020
dc.description.abstractGeuda is a low-quality form of corundum and abundant in the most gem enriched regions in Sri Lanka and can transfer into premium blue sapphires, similar to the natural in appearance through heat treatments. The study intended to identify characteristic features to distinguish heated geuda from natural sapphire using FTIR Spectroscopy. 53 geuda samples were collected from five gem bearing localities Ratnapura, Ridiyagama, Okkampitiya, Bakamuna, and Katharagama and heat treated up to 1800°C for the onehour soaking period under reducing environmental condition. Study samples were subjected to FTIR analysis before and after the heat treatment and could identify the development of a distinctive peak at 3310 cm-1 after treatment. This is due to the diffusion of atmospheric Hydrogen back into the crystal and appears in the absorption spectrum as an interstitial O-H bond in the corundum crystal structure. Further, two absorption bands at 2342 or 2362 cm-1 which corresponds to atmospheric CO2 and CO2 gas in negative crystals were observant in almost of the samples and as a direct response to CO2 gas in negative crystals, the intensity of this particular peak is found to be significantly less for Ridiyagama samples with respect to other localities. This reveals that the Ridiyagama samples are with less CO2 trapped inclusions. Nevertheless, certain 2853 and 2924 cm-1 peaks were observed before and after heat treated stones due to the C-H bond resulted in contamination. Furthermore, 3620 and 3697 cm-1 absorption bands related to Kaolinite hydrous mineral inclusions have been disappeared with heat treatment. This concludes to identify heat treated sapphires with 3310 cm-1 peaks and remaining of 3620 and 3697 cm-1 peaks verify it as a non-heat-treated sapphire. Hence, the FTIR technique could be clarified as one of the best methods to identify heat treated blue sapphires. Keywords: Heat treatment, FTIR analysis, Negative crystals, Absorption spectrum, Inclusionsen_US
dc.identifier.isbn9789550481293
dc.identifier.urihttp://www.erepo.lib.uwu.ac.lk/bitstream/handle/123456789/6096/proceeding_oct_08-458.pdf?sequence=1&isAllowed=y
dc.language.isoenen_US
dc.publisherUva Wellassa University of Sri Lankaen_US
dc.relation.ispartofseries;International Research Conference
dc.subjectMaterials Sciencesen_US
dc.subjectMineral Sciencesen_US
dc.subjectGemstonesen_US
dc.titleInvestigation of Geuda Gemstones, before and after the Heat Treatment using FTIR Spectroscopyen_US
dc.title.alternativeInternational Research Conference 2020en_US
dc.typeOtheren_US
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