Gemstones technique

Year Synthetic gemstone CAS Registry Number Manufacturing technique... 

Table 4. Techniques for Commercial Gemstone Material Synthesis...

Malley, J. (1987), The use of modem analytical techniques in the identification of ancient gems, in Hackens, T. and G. Mucharte (eds.), Technology and Analysis of Ancient Gemstones, Council of Europe, Strasbourg, pp. 41-53. 

Thermal analysis techniques reveal that water is bound in opal in more than one manner. Most of the water is physically held in inclusions or microscopic pores within the opal, that is, in spaces between the microspheres. Water held in this manner can escape through complex systems of microscopic fissures or cracks, induced by temperatures even below 100°C. Some water is held within the opal via chemical bonding ( adsorption ) to the surfaces of the silica microspheres and is retained to temperatures approaching 1000°CJ7J Furthermore, since the microspheres themselves are composed of much smaller silica particles, water is additionally coated on the surfaces of these minute particles. The porous nature of opal and its thermal sensitivity require special care, for dehydration may result in cracking that greatly diminishes the value of this gemstone. 

The most frequently used techniques for the commercial manufacture of synthetic gemstone materials are summarized in Table 4. More details on these can be found in various texts (2,5—7). An overview including the various manufacturers is also available (3). Only rardy used for synthetics are such alternative growth techniques as the Bridgman technique of solidification in a cmcible and the float zone technique, both involving growth from the melt... 

TABLE I. TECHNIQUES FOR COMMERCIAL GEMSTONE MATERIAL SYNTHESIS... 

The following example is a illustration of how photon and charged particles techniques like the micro-PIXE and micro-Raman spectrometry can be combined to solve an important archaeological issue, namely to unveil the intriguing provenance of the red gemstones mounted on barbarian jewels from the early Middle-Ages [11]. 

Nassau, K. (1980) Gems Made by Man, Chilton Book Company, Radnor, PA. An excellent and highly readable account of the techniques used to produce artificial gemstones. Contains lots of history and background information on the processes and their inventors. 

The questions emphasize the need for techniques to aid the eye in examining these materials, or the need to understand the structure and chemistry of gemstones when handling them. 

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