Description
The top five most highly valued gemstones ever sold at auction to date are fancy colour diamonds, due to their exclusivity. This makes diamond-grading reports relevant also to valuing historic items in museum collections, in particular to ascertain current values for insurance or exhibition purposes. Research started back in 2013 (Hainschwang et al.), using the historic green diamonds in the museum collection as untreated reference samples. Next, a selection of twenty rings set with natural blue, pink, green, brown, yellow and white diamonds were examined further. Most of the diamond rings were bought back in the 18th century, or before 1806 at the latest, from the famous ring-stone collection of Emperor Franz Stephan of Lorraine, founder of the museums collection.
Adeline Lageder is a master goldsmith, FEEG Gemmologist and sworn and court-certified expert in the field of jewels, precious metals and gemstones. Since 2006, she has been managing Gemmologisches Labor Austria KG, a renowned contact point for diamond, gemstone and jewellery appraisals with and without valuation.
Dr. Vera M. F. Hammer has the position of a staff scientist in the Natural History Museum Vienna, Department of Mineralogy and Petrography. She is head of the mineral collection and head of the State Gem Institute. As curator of the mineral and gem collection she gives guided tours and organizes scientific field trips. She provides an identification service of minerals, gems and other crystalline substances. In recent years, she has curated a number of permanent exhibitions and participated in several exhibitions and shows outside the museum.
