The basis of the work of the State Institute of Gemmology lies in the large and qualitatively excellent collection of precious stones of the Natural History Museum. This collection is still regarded as the most important of its kind in Europe. The material which comprises this collection as well as the minerals contained in the mineral collection can be used for comparative purposes, when necessary. The collection of precious stones includes some 4 000 objects - raw stones, polished stones as well as some pieces of original jewellery and applied art. In addition to natural products, synthetics and imitations are also included in the collection. Special tours through and exhibitions in the Natural History Museum (e.g., "Tauerngold", "Bodenschätze Sibiriens", "Edel- und Schmucksteine in der Tschechoslowakei" and "Zarenschätze") are offered to relevant institutions, such as, for example, the Viennese Guild of Gold and Silversmiths, the Association of Viennese Gold and Silversmiths, and the Austrian Gemmological Society.