The gemological collection of Abraham Gottlob Werner contains 1374 sample numbers for 25 different minerals with 38 gemological varieties, including 15 newly added numbers of samples, which were not recorded in the original catalog of 1823. In total, 168 samples were recorded as lost by the later researchers, 4 samples were taken for the chain for the rector of the university, samples of 2 different numbers in the catalog were exchanged for cut stones, and 3 times’ volume requisitions happened. A total of 256 sample numbers show discrepancies and therefore are not in accordance with the original record in the catalog. In the collection, 6.8% of the numbers are rock sample with embedded crystals, 20.7% of the numbers are in the form of crystal, 30.6% of the numbers are fragments, 11.6% of the numbers are grains, and the remaining 711 samples are cut. Except for Esa. No. 644a containing four cushion cut samples, all faceted cuts were recorded in the original catalog of 1823. However, the brilliant, oval, step, emerald, scissor, and radiant cut forms were invented after the gemological collection of Werner, which means 189 samples do probably not belong to the original collection. They could be from another collection due to the requisitions, or the later researchers of the collection added or exchanged the samples with new ones. The mineral names of the catalog from 1823 refer to Werner's mineral system, some of the mineral's names are not used anymore. With the development of mineralogy and gemology, the special names of the gemstones as varieties of minerals are gradually standardized. 51 samples are wrong identifications and 8 pieces of glass have been recognized. The zircon samples of the collection provide a research resource for the study of metamictization. Both color and density of zircon could be an indicator of the metamictization degree. The metamictization has a significant influence on the gemological properties of zircon. The green tone and low density cannot be considered as an identifying characteristic of metamict zircon, although they are still a sign of metamictization. Comparing six mineralogical or geological collections at Werner’s time, the catalogs of five collections used his nomenclature of samples and only the catalog of the mineralogical collection of Adolf Traugott von Gersdorf is geographical. To his time the outstanding gemological collection of Abraham Gottlob Werner represented the broadest quantity of gemological varieties. A modern gemological database of the collection has been founded, the meta-data provides an important base for further research and development.:Acknowledgements I Abstract III Table of Contexts IV List of figures VI List of tables VII 1. Introduction 1 1.1 Abraham Gottlob Werner 1 1.2 The mineral system of Werner 1 1.3 The gemological collection of Werner 3 2. Methods 6 2.1 Specific gravity (SG) measurements 6 2.1.1 Hydrostatic weighing 6 2.1.2 He-pycnometer 6 2.2 Color 6 2.2.1 Munsell color system 7 2.2.2 The CIE L*C*h color system 8 2.3 The optical measurements 9 2.3.1 Polariscope 9 2.3.2 Refractometer 10 2.3.3 Dichroscope 11 2.4 Ultraviolet (UV) fluorescence test 12 2.5 Raman spectroscopy 12 3. New model for the inventory of the gemological collection of Werner 13 4. Discussion 16 4.1 Cut cutting in the course of time 16 4.2 Classification of gemstones 24 4.2.1 Individual names of gemstones 25 4.2.2 Different identifications with the catalog of 1823 29 4.2.3 Imitation of gemstones 31 4.3 Raman spectrum study of zircons 32 4.4 Comparison of the outstanding Werner Collection with other collections in the second half of 18th century 39 4.4.1 The natural history collection of Linck family (1638-1807) 39 4.4.2 The Minerals cabinet of Eugen Pabst von Ohain (1718-1784) 40 4.4.3 The natural history collection of the University of Rostock 40 4.4.4 The mineralogical collection of Adolf Traugott von Gersdorf (1744-1807) 41 4.4.5 The mineralogical, geological and paleontological collection of Johann Wolfgang von Goethe (1749-1832) 42 4.4.6 Summary of the additional collections to Werner's time 43 5. Summary 44 Reference 46 Appendix A 59 Appendix B 63 Appendix C 67