A database of Raman spectra of precious gemstones and minerals used as cut gems obtained using portable sequentially shifted excitation Raman spectrometer

Abstract

Raman spectra of 42 minerals, commonly and less frequently used as gemstones in gemmology s. s. or works of arts, have been recorded using a portable sequentially shifted excitation Raman spectrometer. Analyzed minerals include chrysoberyl, diamond, emerald, garnets, magnesiotaaffeite-2N'2S (taaffeite), magnesiotaaffeite-6N'3S (musgravite), ruby, topaz as well as other less precious minerals. Some minerals are represented by several different samples with various causes for fluorescence in order to ascertain the results of the fluorescence removal process on a larger set of natural mineralogical samples. This novel instrumentation is able to effectively suppress the laser-induced fluorescence that is sometimes present in the Raman spectra of natural and often coloured samples of mostly silicate minerals, and at the same time allow the analyses of gemstones and works of arts in situ, which can be important in many cases.

The Reliquary Bust of Saint Lambert from the Liège Cathedral, Belgium: Gemstones and Glass Beads Analysis by pXRF and Raman Spectroscopy

“…Spectra of diamonds contain a single peak located at 1330 cm −1 (Fig. C), in good agreement with the spectra published in the RRUFF database (RRUFF ) and by Culka and Jehlička (). Raman spectra of diamond are very characteristic, the signal is typically strong, and no laser‐induced fluorescence was observed.…”

“…Spectra obtained reveal a strong peak located between 462 and 465 cm −1 , surrounded by other less intense peaks (Fig C). These spectra are in good agreement with spectra from the RRUFF database (RRUFF ) and from Culka and Jehlička (), thus confirming the identification of these gemstones. All spectra for the different quartz samples are fluorescence‐free.…”

“…The spectra were cut at 1400 cm À1 (spectral region between 100 and 1400 cm À1 ) for a better presentation and they were not subjected to any postacquisition data manipulation. The comparative Raman spectra came mainly from the website RRUFF (2019) and Culka and Jehlička (2019) for minerals and from Colomban et al (2006), Colomban (2008) and Tournié (2009) for glass beads.…”

Applications of Raman spectroscopy in art and archaeology

“…Raman spectra of 42 minerals, commonly and less frequently used as gemstones in gemmology s. s. or works of arts, were selected and analyzed by Culka and Jehlička [21] using a portable sequentially shifted excitation Raman spectrometer with the aim to compare the results with this new set-up from the ones obtained with non-sequentially shifted Raman spectrometers. The analyzed minerals included chrysoberyl, diamond, emerald, garnets, magnesiotaaffeite-2 N'2S (taaffeite), magnesiotaaffeite-6 N'3S (musgravite), ruby, topaz as well as other less precious minerals.…”

A comparative mobile Raman study for the on field analysis of the Mosaico de los Amores of the Cástulo Archaeological Site (Linares, Spain)

“…This type of instrument was used for the analysis of painted artworks, [28] and also, some field applications were published for the identification of minerals under extreme conditions. [30][31][32] Bravo uses the sequentially shifted excitation patented technology-SSE ™ , patent number US8570507B1, for fluorescence mitigation by using temperature-tuned diode lasers with wavelengths from 700 to 1,100 nm (DuoLaser ™ -two excitation lasers). [26,33] As reported by Cooper et al, in 2013, [26] the sequentially shifted excitation method deploys a single temperaturecontrolled distributed Bragg reflector diode laser that emits single-mode 785-nm radiation at 25°C.…”