New Mineral Named After GIA’s John Koivula
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 Post subject: Cloudy Diamond
PostPosted: Fri Feb 15, 2019 8:46 pm 
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Greetings!
I am looking for information regarding cloudy diamonds - not diamonds that have a small cloud inclusion or two, but a diamond where its beauty and transparency is severely impacted by a large cloud that is all encompassing.

I have had a couple diamonds like this to grade/appraise in the last few months. Hoping to gain credible information to aid in proper grading and valuing these not so pretty diamonds. Both diamonds are quite large - 1.50ct and 2.12ct. Both exhibited faint yellow fluorescence LW. Viewed under the microscope - it appears that the "cloud" is along a single plane at relatively high relief. Attaching photos - hopefully, the cloudiness can be seen...

Through some research, I have found information leading me to believe that these diamonds might be Hydrogen-rich. This article seems to highlight some information regarding whitish or grayish cloudy diamonds. It does mention planar irregularities - which might also seem relative to what I saw.
https://gem-a.com/images/Documents/JoG/ ... 3_23_8.pdf

I believe that some of these stones are being described as Fancy White diamonds.

Please let me know if you have had any experience with these diamonds. And/or if you know where to access some more information.

Thank you for any and all advice!
Best wishes,
Katy B


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 Post subject: Re: Cloudy Diamond
PostPosted: Sat Feb 16, 2019 12:04 am 
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Hi Katy!
I encountered several of these diamonds, perhaps 15 years ago from Israeli dealers.
They were curious as they had no visible inclusions with 10X magnification to explain the whiteness. And I couldn't find any info about them at the time.

Here is a GIA update:
Image
What is a White Diamond?


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 Post subject: Re: Cloudy Diamond
PostPosted: Sat Feb 16, 2019 1:55 pm 
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Hi, Barbara!
Thank you for your reply. I stumbled upon the same information on GIA's website during my research. Still I am not so sure that the diamonds that I saw were really ones that can be considered white, fancy white or opalescent. I think they might be stuck somewhere in the middle! Here is another article dug up from the depths (almost 80 years old) about diamonds from the Panna Mine. https://www.ias.ac.in/article/fulltext/ ... /0334-0342

Still hoping to find a more conclusive way to classify and grade these diamonds. Since I felt so uneasy with the diamond over 2cts - I had to let my client go with the suggestion that he send the stone to GIA's lab for testing and grading. He still wanted an idea of value - I had to tell him that since the evaluation and grading was inconclusive - there wasn't anyway I could even approach assigning a value. Obviously, no payment for the 1.5 hours studying/evaluating the diamond/ring; but I'm chalking it up to experience and a learning exercise!

Thanks again and best wishes,
Katy B


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 Post subject: Re: Cloudy Diamond
PostPosted: Sat Feb 16, 2019 2:17 pm 
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Cool - like milk in water...

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 Post subject: Re: Cloudy Diamond
PostPosted: Sat Feb 16, 2019 2:20 pm 
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Leibish usually sells these
https://www.leibish.com/white-diamonds
www.leibish.com wrote:
Image
Colored diamonds are an anomaly in the natural world. Colorless diamonds outnumber color diamonds at a rate of about 10,000 to 1. Diamonds can come in many different naturally occurring colors, and the different colors occur due to different causes. White diamonds are diamonds that have a perceived color hue resembling white powder or refined sugar, and actually demonstrate an inherent opaque snow-white color. Unlike the characteristic cause in the rest of the colors of natural fancy color diamonds, the color white in fancy white diamonds is not the result of a compound element. They are actually colorless diamonds that contain a high concentration of submicroscopic inclusions that scatter light, yielding a distinctive frosty "milky" white face-up color. The nature of these submicroscopic inclusions is unknown, although they are thought to be the result of nitrogen within the diamond’s pure carbon structure.

As White is a neutral color, Natural Fancy White Diamonds are not measured by their level of saturation but rather designated only as Fancy White. Fancy White diamonds are not divided by degrees of clarity. Fancy white diamonds are quite difficult to find, although Leibish & Co. offers a selection in assorted shapes and carat weights.


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 Post subject: Re: Cloudy Diamond
PostPosted: Sat May 11, 2019 5:01 pm 
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Cloudy diamonds are not fancy colored diamonds. Those are somewhere between transparent and translucent which detract from the value of one that has a particular color, clarity and cut grade that is transparent.

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 Post subject: Re: Cloudy Diamond
PostPosted: Sat May 11, 2019 8:16 pm 
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There are two causes of cloudy white diamonds.

One is the most common, a cloud. A cloud is a clarity feature that affects the grade and value of a diamond as does any clarity feature. If it covers the whole of the stone, and is visible to the naked eye it is most likely some level of Imperfect grade.

The other cause is fluorescence. Pure white fluorescence is rare, more often there is some minimal yellow component if studied closely. As with any fluorescence it can affect transparency. Stones pay a heavy price penalty for this level of fluorescence.


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 Post subject: Re: Cloudy Diamond
PostPosted: Sat May 11, 2019 8:48 pm 
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A fancy white diamond is considered "fancy" by the GIA.
They, in my opinion, are collectible curiosities which do not command the prices of other natural fancy colors.

The white diamonds I encountered had no visible inclusions with 10X mag. The inclusions within them were apparently submicroscopic, therefore not seen with standard gem microscopes.
They also were not fluorescent.
I remember that because it was one of the first things I checked.


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 Post subject: Re: Cloudy Diamond
PostPosted: Sat May 11, 2019 9:40 pm 
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I love stones with a bit of rayleigh scattering. Definitely more interesting to me than a normal diamond, but that doesn't mean anything to the actual market.

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 Post subject: Re: Cloudy Diamond
PostPosted: Sat May 11, 2019 10:10 pm 
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Barbra Voltaire wrote:
A fancy white diamond is considered "fancy" by the GIA.
They, in my opinion, are collectible curiosities which do not command the prices of other natural fancy colors.

The white diamonds I encountered had no visible inclusions with 10X mag. The inclusions within them were apparently submicroscopic, therefore not seen with standard gem microscopes.
They also were not fluorescent.
I remember that because it was one of the first things I checked.


If the GIA has declared cloudy diamonds as a fancy color, that is misguided and unrealistic. Those stones have been and are rejected in the market in favor of transparent stones. No jeweler or dealer I know of wants cloudy stones.

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 Post subject: Re: Cloudy Diamond
PostPosted: Sat May 11, 2019 10:59 pm 
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A cloud in a diamond is an inclusion which can be seen (and plotted) with a 10x microscope.

White diamonds appear white as the result of the elastic scattering of light by submicroscopic particles much smaller than the wavelength of the radiation. (aka Rayleigh scattering, thank you Stephen).

Moonstone's blue sheen is also the result of Rayleigh scattering.

This is super cool, but not to everyone's taste. A rather affordable collectible curiosity.


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 Post subject: Re: Cloudy Diamond
PostPosted: Sun May 12, 2019 6:15 pm 
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Barb, I think we agree on the fundamentals, but employ slightly different terminology. You correctly cite the gemological term "cloud" used as a noun for an aggregate inclusion. I use the adjective "cloudy", which does not reference the gemological term, but rather the common english term meaning "not transparent or clear" applied to the condition in this case scientifically called Rayleigh scattering.
In every instance I have been asked to recut a cloudy diamond, the jeweler has asked me to do something about the cloudiness, even thinking it might have been caused by oxygen etching. At best, I can only change the angles to improve reflection a small amount, but advise it probably will not increase the value of the stone.

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 Post subject: Re: Cloudy Diamond
PostPosted: Sun May 12, 2019 6:43 pm 
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I agree that my first reaction when seeing these white diamonds was to stick them in the sonic thinking they would clean right up.......


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