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The Role of Silicon in the Color of Gem Corundum

Emmett, John L. and Stone-Sundberg, Jennifer and Guan, Yunbin and Sun, Ziyin (2017) The Role of Silicon in the Color of Gem Corundum. Gems and Gemology, 53 (1). pp. 42-47. ISSN 0016-626X.

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Natural corundum is colored by a variety of trace-element impurities and by the chemical reactions among them. Important to nearly all of the colors is the role played by the reactions among silicon, titanium, and magnesium. Characterization of the interactions between these aliovalent ions has been hindered by the fact that the laser ablation–inductively coupled quadrupole–mass spectrometry equipment used in most gem labs does not resolve the interferences for silicon. Thus Si has not been measured at relevant concentrations. Recent development of ion implant standards and the application of secondary ion mass spectrometry has allowed the accurate measurement of silicon in corundum for the first time. As an example of its importance, detailed analyses of sapphire from Montana’s Yogo Gulch deposit are presented. These analyses show that without silicon, Yogo sapphire would not be blue.

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Guan, Yunbin0000-0002-7636-3735
Additional Information:© 2017 Gemological Institute of America. Tom Moses and GIA have provided long-term support for numerous studies like this one. Tim Thomas initiated GIA’s development of the new set matrix-matched standards on which this work depends. He had the foresight to include an ion implant standard for silicon, which made this work possible. Dr. George Rossman has facilitated access to Caltech’s excellent SIMS analytical facility. In addition, he continues to provide an extremely helpful debate of the technical issues, which is greatly appreciated.
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Record Number:CaltechAUTHORS:20170608-075737410
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78024
Deposited By: Tony Diaz
Deposited On:08 Jun 2017 21:24
Last Modified:27 Nov 2019 00:14

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