Comparison of seven portable Raman spectrometers : beryl as a case study

In this paper, a series of beryl varieties with the accent on emeralds was investigated using seven portable Raman spectrometers equipped mainly with 785- and 532-nm excitation lasers. Additionally, one dual system and a new portable sequentially shifted excitation Raman spectrometer were applied. The advantage of using handheld instrumentation for investigations to be carried out outside the laboratory is well documented. For major part of beryls (emeralds and aquamarines), the most intense Raman bands are found at correct positions +/-2 to 4cm(-1) using all the instruments (with the exception of one). Unambiguous identification of beryls is ensured by obtaining the strong characteristic of Raman features (1070 and 686 cm(-1)) of the whole spectrum. Spectroscopic performance and differences existing between the instruments not only from the construction and ergonomic point of view are discussed. All the instruments tested EzRaman-I Dual (Enwave Optronics), RaPort (EnSpectr), FirstGuard (Rigaku), FirstDefender XL and FirstDefender RM (Thermo Scientific), Inspector Raman (Delta Nu) and Bravo (Bruker) can be used for common gemmological and mineralogical work in situ. Two instruments (the RaPort and the sequentially shifted excitation Raman spectrometer Bravo) allow recording excellent quality Raman spectra comparable with laboratory dispersive Raman microspectrometers