Distinguishing natural from synthetic amethyst: the presence and shape of the 3595 cm−1 peak     

S. Karampelas  E. Fritsch  T. Zorba  K. M. Paraskevopoulos  S. Sklavounos 《Mineralogy and Petrology》2005,85(1-2):45-52

Summary The infrared absorption spectrum of amethyst in the region of stretching vibrations of X–OH groups reveals several bands that have been used for the separation of natural from synthetic amethyst. The intensity and shape of these bands have been measured as a function of crystallographic orientation. Using a resolution of 0.5 cm⁻¹ the 3595 cm⁻¹ band is present in all infrared spectra of natural amethyst and in some rare synthetic ones. If present in synthetic amethyst, its full width at half maximum (FWHM) is about 7 cm⁻¹ whereas it is about 3 cm⁻¹ in all natural samples. This new criterion, unlike the previous ones, seems appropriate to separate natural from synthetic amethyst in all cases.  相似文献   

Luminescence spectroscopy and microscopy applied to study gem materials: a case study of C centre containing diamonds     

Thomas Hainschwang  Stefanos Karampelas  Emmanuel Fritsch  Franck Notari 《Mineralogy and Petrology》2013,107(3):393-413

The methods of luminescence spectroscopy and microscopy are widely used for the analysis of gem materials. This paper gives an overview of the most important applications of the analysis of laser and UV excited luminescence by spectroscopy and visually by microscopy with emphasis on diamond, and specifically natural type Ib diamond, little studied so far. Luminescence based techniques are paramount to the gemmological analysis of diamond, in order to determine whether it is natural, treated or synthetic. The great sensitivity of luminescence helps detect some emitting centres that are undetectable by any other analytical method. Hence, especially for diamond, luminescence is an enabling technology, as illustrated by its pioneering use of imagery for the separation of natural and synthetic diamond, and of spectroscopy for the detection of High Pressure–High Temperature treatment. For all other gemstones the applications are at the moment less numerous, but nevertheless they remain highly important. They provide quickly information on the identification of a gem material, and its treatment. Besides the study of broad band emissions caused by various colour centres, the typical PL-causing trace elements (amongst others) are chromium, manganese, uranium and rare earth elements. In pearls the study of broad band luminescence can be useful, and particularly the study of pink to red porphyrin luminescence in pearls from certain species such as Pinctada and Pteria and others can help identify the pearl-producing mollusc, or if a pearl has been dyed or not. Type Ib diamonds are representative of the importance and complexity of the analysis of luminescence by microscopy and spectroscopy. They show a wide range of sometimes very complex emissions that result in luminescence colours from green to yellow to orange or red. These emissions show generally very inhomogeneous distribution. They are caused by a range of defects, however only a few of them are well characterized.  相似文献   

New Data on the Genetic Linkage of the Beryl and Chrysoberyl Chromophores of the Ural’s Emerald Mines with Chromium-Bearing Spinels of the Bazhenov Ophiolite Complex     

Popov  M. P.  Sorokina  E. S.  Kononkova  N. N.  Nikolaev  A. G.  Karampelas  S. 《Doklady Earth Sciences》2019,486(2):630-633

Doklady Earth Sciences - The distribution of chromophores and the composition of chromium-bearing spinels in Uralian emeralds and alexandrites were studied for the first time. It was prooved the...  相似文献