Stefanos Karampelas is Chief Gemmologist at the Laboratoire Français de Gemmologie (LFG), Paris, and he is also lecturing for the Advanced Gemmology Diploma at the University of Nantes, France. He started studying Geology and Mineralogy at Aristotle University of Thessaloniki (Greece), he has MSc in Geosciences and Advanced Gemmology Diploma, both from the University of Nantes (France), and he completed his PhD in Materials Physics at the University of Nantes (France) and Mineralogy at the Aristotle University of Thessaloniki (Greece) on the non-destructive study of the origin of pearls' color. He worked as a Research Scientist for about 7 years at Gubelin Gem Lab and a further year at GemResearch Swisslab, both in Switzerland, as well as for about 3 years as Research Director for the Bahrain Institute for Pearls and Gemstones (DANAT). His research interests include advanced non-destructive techniques applied to all kind of gem materials. He has published numerous peer-reviewed articles in scientifc journals, contributed to books, and visited several gem mines as well as natural and cultured pearl producing areas around the globe. He is also frequently delivering lectures to international scientifc conferences and gemmological meetings. He is a Member of the Commission of Gem Materials of International Mineralogical Association and of the Editorial Board of Gems & Gemology, Delegate for the International Gemmological Conference, and Associate Editor of The Journal of Gemmology.

Lore Kiefert is Chief Gemmologist at Gübelin Gem Lab, where she is, among other tasks, responsible for the training of gemmologists. She started studying Mineralogy in Heidelberg, Germany, in 1981 and completed her Master's thesis on the origin of sapphires in 1987. She then moved to Australia to study themineralogical and chemical composition of desert dust, which earned her a PhD in 1996. Leaving Australia for Switzerland in 1994, she joined the SSEF Swiss Gemmological Institute as Deputy Director and went on to become its Director of the Coloured Stones Department as well. During her time at the SSEF, she completed her FGA Diploma in 1998. In 2005, Lore moved to New York to head the AGTA Gemmological Testing Center as Laboratory Director until she decided to return to Europe to join the Gubelin Gem Lab as Chief Gemmologist in October 2009.

She has authored and co-authored over 100 publications in gemmological and scientific journals, as well as chapters in textbooks such as the Handbook of Raman Spectroscopy. She regularly delivers gemmological lectures at conferences worldwide and has co-organised two gemmological conferences in Switzerland and the USA. Lore is also on the editorial review board of Gems & Gemology and the Journal of Gemmology, as well as member of the LMHC. Dr. Kiefert was awarded professorship at Tongji University in Shanghai, China in 2017, where she regularly conducts workshops and lectures.

Danilo Bersani is associate professor in physics at the University of Parma, Italy, Department of Mathematical, Physical and Computer Science. His research is mostly devoted to the spectroscopic analysis of gems, minerals, nanocrystalline materials, objects related to art and archaeology, in particular by means of Raman spectroscopy. He is author of more than 150 scientific publications in international journals and has given more than 250 presentations at international conferences. Organizer and member of the scientific committees of different international conferences, such as GeoRaman, inArt, RAA (Applications of Raman Spectroscopy in Art and Archaeology).

Peter Vandenabeele is professor in archaeometry at Ghent University, Belgium. He is member of the department of archaeology and associated member of the department of chemistry. In 2000, he obtained his PhD in analytical chemistry with research on the application of Raman spectroscopy and total-reflection X-ray fluorescence for the analysis of art objects. His research mainly focusses on the development and optimisation of spectroscopic techniques for archaeometrical applications. He authored the handbook 'Practical Raman Spectroscopy: An Introduction' and co-edited several other books. He is author of peer-reviewed research papers and frequently presents his recent research in international scientific conferences and is chairman and committee member of international conferences in the fields of art analysis and Raman spectroscopy.

Introduction.- Gems through the ages.- Gem analysis.- Gem treatments, synthetics and Imitations.- Archaeometrical questions (case studies).- Glossary.