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CVD Lab-Grown diamonds might change colour?

OoohShiny

Ideal_Rock
Premium
Joined
Apr 25, 2014
Messages
6,856
@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!



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.
 

SJEsper

Rough_Rock
Joined
Jul 30, 2019
Messages
33
Thanks for posting this @OoohShiny . As a scientist by trade, I noticed that the title claims of CVD Diamonds is color unstable is based on just 1 diamond.

With a sample size of 1 diamond, it's more likely this is a statistical anomaly rather than a fact.

It's rather misleading and given the nature of the site is geared towards mined diamonds, I wonder if there is a vested interest in presenting the information as such.

The Diamond Producers Association ( the diamond industry’s joint category-marketing effort) are trying to shape the narrative of how consumers perceive lab diamonds and mined diamonds, with mined diamonds as better (and thus maintain their current market value) with a new marketing campaign

"3 Billion Years in the Making"
""Real Is Rare"

1576028545570.png

I agree with what the GSI lab is suggesting in terms of how to perform testing going forward, but more CVD diamonds with a substantial sample size needs to be tested in order to put forth this claim as reliable.
 

OoohShiny

Ideal_Rock
Premium
Joined
Apr 25, 2014
Messages
6,856
Thanks for posting this @OoohShiny . As a scientist by trade, I noticed that the title claims of CVD Diamonds is color unstable is based on just 1 diamond.

With a sample size of 1 diamond, it's more likely this is a statistical anomaly rather than a fact.

It's rather misleading and given the nature of the site is geared towards mined diamonds, I wonder if there is a vested interest in presenting the information as such.

The Diamond Producers Association ( the diamond industry’s joint category-marketing effort) are trying to shape the narrative of how consumers perceive lab diamonds and mined diamonds, with mined diamonds as better (and thus maintain their current market value) with a new marketing campaign

"3 Billion Years in the Making"
""Real Is Rare"

1576028545570.png

I agree with what the GSI lab is suggesting in terms of how to perform testing going forward, but more CVD diamonds with a substantial sample size needs to be tested in order to put forth this claim as reliable.
An excellent response, thank you - I admit I skim read it before posting, which is my fault!

Rapaport's position on MMDs is indeed pretty clear, lol:


I would be interested in finding out what the "high-powered ultraviolet (UV) rays" were - if they were far higher in intensity/energy than one would see even after a full day in the sun, that would hardly be a realistic test of its day-to-day properties.

Given the volume of MMDs being produced, I am sure that we would know about it by now if it was an inherent and widespread problem!

And, besides, even if they did turn blue, who doesn't like a blue diamond? :D
 
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