- Apr 25, 2014
@Texas Leaguer was kind enough to flag this story up in another thread - I thought it was really interesting and not something we've seen reported to date, so worthy of attention!
Garry, The fact that alternate technologies exist or new technologies emerge does not necessarily invalidate older studies. You have mentioned numerous times that in your opinion the Cowing study used the wrong device to measure light content or intensities, and that it was focused on the wrong...
RAPAPORT... Synthetic diamonds grown using chemical vapor deposition (CVD) could change color for an extended period following exposure to certain light forms, Gemological Science International (GSI) has warned. When testing a 2-carat CVD diamond, GSI exposed the stone to high-powered...
Lab Warns of Color Instability in CVD
Dec 4, 2019 10:32 AM By Leah Meirovich
RAPAPORT... Synthetic diamonds grown using chemical vapor deposition (CVD) could change color for an extended period following exposure to certain light forms, Gemological Science International (GSI) has warned.
When testing a 2-carat CVD diamond, GSI exposed the stone to high-powered ultraviolet (UV) rays, during which it went from near colorless to blue, the organization said Tuesday. This blue coloring remained despite a week in a vault, GSI explained.
Although CVD diamonds are known to change color under strong UV lighting or extreme heat, they generally return to normal after 30 minutes to an hour of direct sunlight, GSI noted. However, the stone in question took two-and-a-half hours to return to its regular hue, it added, warning that color changes in CVD may occur through casual use.
“When wearing [them] out in the open, CVD diamonds may change in coloration upon even subtle exposures to electromagnetic radiation, such as UV rays on a sunny beach, or under a blacklight in a nightclub, for example,” said GSI chief information officer Nicolas Del Re.
The stones change color due to photochronism, a process by which the electrons in defects within the CVD diamond cause the energy state to change, thereby affecting the way color is absorbed on the visible spectrum, the organization explained.
“It is strongly suggested that all laboratory-grown CVD diamonds are placed in a full-spectrum light box for at least 30 minutes before color grading,” Del Re added.