Khan, Rizwan U. A., Martineau, P. M., Cann, Bradley L., Newton, Mark E., Dhillon, Harpreet K. and Twitchen, Daniel J.. (2010) Color alterations in CVD synthetic diamond with heat and UV exposure: implications for color grading and identification. Gems & Gemology, Vol.46 (No.1). pp. 18-26. ISSN 0016-626X

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Abstract

In response to heat and UV exposure, some synthetic diamond gemstones grown by chemical vapor deposition exhibit large, reversible changes in color. A significant reduction in color was achieved by heating several CVD synthetic gemstones to >450 degrees C. Conversely, a darker color was observed in samples following exposure to UV radiation (such as that used in gem testing). Both the heated and UV-exposed samples returned to their initial (stable) color when they were illuminated for >30 minutes with a standard daylight-equivalent lamp used for grading. However, these color states did not change with time when the samples were kept in the dark. Heating and UV exposure also influenced the strengths of various IR absorption features that might be used to identify such a sample as a CVD synthetic. These nonpermanent changes might affect the apparent color grade of a CVD synthetic diamond, and care must be employed in the interpretation of spectroscopic features used to determine a stone's natural or synthetic origin.

Item Type:	Journal Article
Subjects:	Q Science > QE Geology
Divisions:	Faculty of Science > Physics
Journal or Publication Title:	Gems & Gemology
Publisher:	Gemological Institute of America
ISSN:	0016-626X
Date:	2010
Volume:	Vol.46
Number:	No.1
Number of Pages:	9
Page Range:	pp. 18-26
Identification Number:	10.5741/GEMS.46.1.18
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
URI:	http://wrap.warwick.ac.uk/id/eprint/5952

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