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The present research concerns the characterization of samples of corundum (Al 2 O 3 ), varieties of sapphire, by micro-Raman spectroscopy. Ten samples of natural corundum from Australia, Madagascar, Sri Lanka, Thailand, Tanzania, and Vietnam were studied. After standard gemmological analysis, micro-Raman analysis was also performed in order to identify mineral inclusions within the sapphire samples and to obtain information on the geological genres of the minerals. Several inclusions were evidenced within the sapphires and identified by Raman spectroscopy thanks to a confocal spectrometer, which allowed detection also below the external surface of the gem. Finally, the Raman spectra are discussed taking into account the provenance of the samples and their optical absorption.

A new production of hydrothermal synthetic emeralds, grown in the Czech Republic with Italian technology, has been marketed since December 2004 with the trade name Malossi synthetic emerald. Several samples were investigated by standard gemological methods, combined with chemical analyses and UV-Vis-NIR and IR spectroscopy. A comparison of this material with natural and other synthetic emeralds (the latter grown by the flux and hydrothermal techniques) reveals that Malossi hydrothermal synthetic emerald can be identified on the basis of microscopic features and chemical composition, along with the mid-infrared spectrum.

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This article presents a full characterization of a suite of aquamarines and other blue beryls of different origins by classic gemological and contemporary analytical techniques, in order to determine those features that may be diagnostic for their identification. MATERIALS AND METHODSWe examined a total of 25 natural, treated, and synthetic blue beryl specimens (see, e.g., figure 1): four faceted Brazilian aquamarines (0.18 to 1.54 ct); one faceted and one rough aquamarine from Nigeria (1.81 and 54.02 ct, respectively); three faceted (0.08-0.13 ct) and two rough (7.30 and 8.20 ct) aquamarines (marketed as "True Blue" beryl) from the Yukon Territory, Canada; one faceted Maxixe-type (irradiated) blue beryl (1.77 ct); three faceted Tairus hydrothermal synthetic blue beryls (2.03-3.50 ct);Aquamarine, Maxixe-type (irradiated) beryl, and two types of hydrothermally grown synthetic blue beryl currently available in the marketplace were investigated by classical gemological methods, chemical analysis, and UV-Vis-NIR and mid-IR spectroscopy. These materials may be conclusively identified by a combination of these techniques. The Maxixe-type beryl (like naturalcolor Maxixe beryls) is distinguishable by its unusual dichroism, green UV fluorescence (when present), Fe-free chemical composition, and distinctive UV-Vis-NIR spectrum. The hydrothermal synthetic blue beryls can be discriminated from their natural counterparts on the basis of microscopic features, chemical composition, and visible and infrared spectroscopic features.