Blog der Deutschen Gemmologischen Gesellschaft

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Herausgeber: 
Deutsche Gemmologische Gesellschaft e.V.
Prof.-Schlossmacher-Str. 1
D-55743 Idar-Oberstein

 

Copyright:
Für alle Beiträge behält sich die Deutsche Gemmologische Gesellschaft (Deutsche Gesellschaft für Edelsteinkunde) e.V. sämtliche Rechte vor, insbesondere die des Nachdrucks, der Übersetzung in andere Sprachen und der photomechanischen Wiedergabe. Die veröffentlichten Beiträge stellen – soweit namentlich bezeichnet – die Auffassung der Autoren dar und geben nicht notwendig die Meinung von Herausgeber und Schriftleitung wieder. (Content of this journal may not be reproduced in any form without the permission of the German Gemmological Association. Opinions expressed do not necessarily reflect the views of the Association.)

Measurement of the Cape line in a natural diamond with a portable photoluminescence spectrometer.

The field of Gemmology with its gemmological examination methods is constantly evolving. Classical methods such as investigation with polariscope, refractometer and microscope will always be of particular importance in the characterization of gemstones and organic substances. More complex analyses such as recordings of spectra with spectrometers and chemical analyses were for a long time reserved for large gemmological laboratories.

In the last years, mobile spectrometers have become more widely accessible, which allows the practicing gemmologists to carry out a variety of additional examinations. It also expands the gemmologist's responsibility. The examination of a blue tourmaline, for example, no longer just involves determining the type of mineral; the identification of the variety is also of great importance. Whether a blue tourmaline is coloured by copper, and thus a Paraiba tourmaline, or by iron, and thus an indicolite, cannot be determined with traditional examination methods. However, measuring a simple absorption spectrum in the visible and near infrared spectral range provides the answer.

 

PL Spectroscopy Zeichenfläche 1Schematic sketch of the measurement of a photoluminescence spectrum.

 

One of the biggest challenges currently is the identification of synthetic diamonds. Even though many “quick testing devices” have been developed and classical examination methods also enable a distinction, more advanced devices such as infrared and Raman spectrometers, as well as measuring of absorption and photoluminescence spectra, allow a much more precise characterization, including possible evidence of treatments.

There are numerous examples for a useful expansion of examination methods, from the detection of synthetic stones (e.g. diamonds, spinel etc.), to the differentiation of varieties (e.g. emerald vs. iron-coloured beryl, chrome tourmaline vs. verdelite etc.), to the identification of untreated cultured pearls or the detection of artificial fillers and dyes in opaque stones such as turquoise or lapis lazuli.

 

web 20160811 DGemG 1699Basics of colorimetry.

 

The seminar “scientific methods in gemmology” addresses these modern examination methods and applies them in practice, with a focus on mobile devices in comparison to the stationary equipment in the gemmological laboratory. In addition to the practical application, a main goal is to train the understanding of the theoretical background of the respective methods, to discuss possibilities and limitations, learn to interpret the most useful spectra and get advice on how to build a well-founded database independently.

 

The following methods are discussed in detail:

    • UV/Vis/NIR spectroscopy, as well as colour causes and colour measurement
    • Photoluminescence spectroscopy
    • Raman spectroscopy
    • Infrared spectroscopy (FTIR)
    • Chemical analysis

The next seminar in English language will take place from November 25th to 29th, the seminar fee is 750€.

If you are interested, This email address is being protected from spambots. You need JavaScript enabled to view it.!

 

 

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