Lectures from leading Gemmologists, Dealers, and Diamond Experts on a broad range of subjects but crucial topics that are most worrisome to Jewellers, Gem Dealers and Appraisers.
Adeline Lageder (Gemmologisches Labor, Austria)
Dr. Vera M.F. Hammer (Natural History Museum, Austria)
Historic diamond rings from the Natural History Museum Vienna – Appraising the invaluable?
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.
Difficulties can occur when examining mounted diamonds as the 4Cs cannot be determined with 100% accuracy. FTIR, UV-Vis-NIR, fluorescence and photoluminescence spectra were recorded at room temperature.
Alberto Scarani, Mikko Astrom (MAGILABS, USA, Finland)
Advanced Instruments for testing of Gems and Diamonds
Abstract coming soon
Branko Deljanin (CGL lab, Canada)
Historical Review of Detection Instruments for Diamonds of Different Origins
Is overview of use of screening and identification instruments in last 25 years when colorless Laboratory Grown Diamonds (LGD) were rare, up to now, with industry-wide shift towards laboratory-grown diamonds.
While well-equipped labs can identify LGDs and issue a report accordingly, the science of diamond no longer resides in the lab, as diamond dealers, gemmologists, appraisers, and retailers need help to at least screen and identify natural and laboratory-grown diamonds. Recently, a growing number of detection tools have been developed using several different screening or detection methods. There are over 70 instruments on the market, so diamond trade is confused on proper use and interpretation of results.
It is strongly recommended to test each diamond in question with minimum 3 instruments, as there is no single instrument from any of 4 groups (standard, UV transparency, luminescence and advanced) that could give all the time 100% ID of diamond in question.
Dr. Claudio C. Milisenda (DSEF German Gem Lab, Germany)
An in depth look at Paraiba Tourmaline
Tourmaline surpasses all other gemstones by its wide range of colours. At the end of the 1980s, unusual vivid blue and green elbaite tourmalines from the Paraíba State in northeastern Brazil generated major interest in the gem trade due to the discovery of new colours that had never been seen before in this gemstone species.
At the turn of the millennium, copper and manganese bearing tourmalines from the Oyo state in Nigeria came into the market. Today most copper bearing tourmalines offered on the market come from alluvial deposits in the east part of the Alto Ligonha pegmatite area in northeastern Mozambique.
This presentation will focus on the geology, compositional characteristics, nomenclature, enhacement, origin determination and imitations of Paraiba tourmaline.
Dr. Clemens Schwarzinger (Johannes Kepler University, Austria)
Zoisite – an Austrian Slovenian story with some impact from Tanzania
Zoisite is a mineral that was first found in Austria and then named after the Slovenian noble man Sigmund Zois, Freiherr von Edelstein. However, its real popularity only came when the blue variety, later to be named tanzanite, was found in Tanzania in the 1960ies. In this talk we will not only focus on the blue variety of zoisite but also discuss other colors, such as green, pink, yellow, or orange, their trace element composition and how it influences the color.
It is also common knowledge that many zoisites are heat treated to display their blue color, but also other colors can be achieved by heat treatments. Spectroscopic techniques such as mass spectrometry, UV-Vis, Raman and FTIR spectroscopy will be discussed to investigate their potential in identifying treatment of zoisites.
Dr. Jaroslav Hyrsl (consulatant, Czech republic)
Genetic classification of mineral inclusions in quartz
The following types of geological environment are producing the majority of inclusions in quartz. For each type the examples of main localities and typical inclusions will be given. They are numbered according to an approximate volume of the specimens, the Alpine fissures being by far the most common ones:
- Alpine fissures
- Granitic pegmatites
- Tungsten deposits
- Dolomitic carbonates
- Ore veins
- Alkaline pegmatites
- Quartz monomineral veins with amethyst
- Amethyst geodes in volcanic basalts
- Skarn deposits
Dr. Lore Kiefert (Gemmological Consultancy Company, Germany)
Historical aspects of gemstone origin and its detection
The history of gemstone mining is as old as mankind. Jade was already mined as far back as 9000 BC in ancient China, and the Egyptian emerald mines go back to 1800 BC. Rubies and sapphires from Sri Lanka and Myanmar have been found in ancient jewellery that goes back over 2000 years, similarly old as the Golconda diamond mines in India.
The Silk Road in Asia and Roman trade roads made it easy to distribute such precious goods into other parts of the world, and from the Middle Ages on, Spanish and Portuguese seafarers brought emeralds and pearls from the Americas with them.
Since then, more and more mines have been found in all parts of the world. Especially in the second half of the 1950s up to now, a multitude of new gem deposits have been found not only in the already known countries, but increasingly in Africa. This trend made gems from the “classic” sources more desirable than their newer relatives, and the task of gemmological laboratories was not only restricted to the determination of authenticity and treatment, but also to origin determination.
The pioneers of gemstone identification, such as Dr. Edward Gübelin, who had been visiting gemstone mines since the 1930’s, had the opportunity to collect original material and could build on it when new mines were discovered and build up a substantial reference collection.
However, with the current multitude of mines with overlapping properties, microscopy and classical gemmology together with a comprehensive reference collection is not sufficient anymore, and laboratories had to consistently upgrade their equipment to keep up with these developments.
The lecture concentrates on the developments of gem mines worldwide and shows ways how origin determination of gemstones is performed in major gemmological laboratories nowadays.
Dr Miha Jersek (Slovenian Museum of Natural History, Slovenia)
Gemstones from Zois mineral collection
Slovenian Museum of Natural History keeps one of the bigest mineral collection in this part of a Europe from more then 200 years ago. It was collected by Sigismondo Zois (1747 – 1819). This mineral collection was the founding collection of a first museum in Slovenia, which was established in 1821. The collection is famous because of typical mineral specimens from mines and some gem quality minerals.
Zoisite samples from Saualpe in Carinthia (Austria), have a special place among minerals, which represent the type material of this mineral. The mineral was originally called saualpite, but the famous mineralogist Werner named it zoisite in 1805 in honor of Zois. Today, the gem specimens of this mineral from Tanzania are known as tanzanites, as green zoisite in the aniolite rock from Africa, and as pink zoisite with an admixture of manganese from Norway, which is known as thulite.
Among the gems, we can point out the Zois diamond, olivine crystals from the island of Zabargad in the Red Sea, green beryl and aquamarines from the Ural mountains, and some others, which today represent the type material of some gemstones.