Pros . . . what is "even" color distribution?

[kenny]

One of the grades GIA gives to FCDs is for distribution of color.
Usually it is even, but I'll post examples of Uneven, and Not Applicable.

Here is an example of one with "even" color distribution, but look at it.
That's not even, or is it?

I see places with much more color than other places and the shape of the more color-saturated area is not related to cut or facets or reflections.
Clearly I have no idea what GIA means by color distribution.

 

[kenny]

Here's a new Grayish-Violet pear that I just bought.
Clearly it has stronger color near the tip, which I suspect is related to cut, not variations in the saturation of the rough.

Still, it got an Even Color Distribution grade.

 

[kenny]

To rephrase the question . . . does anyone know if GIA's Color Distribution grade is about the nature of the rough, the result of the cut or both?

Is is measured only face up?

 

[slg47]

kenny, what did the new orange get as far as color distribution?

 

[kenny]

kenny, what did the new orange get as far as color distribution?

Even.

 

[kenny]

This one was graded Not Applicable.
What the heck does that mean?

 

[kenny]

This one got an uneven grade.

 

[kenny]

This is EVEN color distribution per GIA.

What's going on, and why hasn't this question come up before? (as far as I know)

 

[yssie]

Great question, no idea, and good grief that last rock is

 

[kenny]

This is on GIA's website but it doesn't explain the discrepancies I see in the above examples.

http://www.gia.edu/lab-reports-services/diamonds/diamond-reports/index.html
Click on, "GIA Colored Diamond Grading Report".
Then click on, "View Report Anatomy".
Then if you hover your cursor over "Color Distribution" it reads, "Describes the evenness or unevenness of color seen face-up using standard viewing procedures."

For some reason, even though I see the description on on my screen, my screen-capture tool does not capture them here.

Is there a GG in the house?

 

[AN0NYM0US]

Not Applicable is for diamonds in the less than fancy grade. Everything from Faint to Light get a "Not Applicable" distribution.

As for the pics not showing the even distribution, I believe it is the fault of the pic and not GIA. Your Violet looks much different to me than the vendors pic of it, not regarding distribution but rather the color. Vendors pics are not always accurate representations.

 

[AN0NYM0US]

An "Uneven" can occur from a very small part of the diamond not having the same saturation. It does not have to be a significant amount at all.

 

[Leibish & Co.]

That's an excellent topic Kenny,

Even and uneven are the way the color distributes on the stone, in case the color isn't distributed equally along the stone, it will be graded as uneven,
Uneven are more likely to be found in the following shapes: Emerald, Baguettes, Princess cut and Briolette.
I'm enclosing a pic of 0.12ct FBG Baguette we used to own, you can see the center part of the stone doesn't have the same color like the sides, and indeed GIA graded this stone as uneven

Due to the cut of this shapes it's more possible the color will be distributed unevenly in the stone.

Bow tie you see in Pear shape, Marquise and Oval isn't uneven color, since it is part of the cut of the stone..
It also possible if the stone has a cloud on certain point or a color patch and it causes an unequal color distribution.

Not applicable is like anonymous said, for stones that are below Fancy in Grade(between Faint and Fancy Light.

Best

Itzik Polnauer

 

[clgwli]

My initial thought was that the uneven "look" had to do with the clarity grade and not the color distribution. I do know that tips of some cuts will look uneven (like your pear) in spite of them really being even.

I admit that is something I do pay attention to with colored diamonds. I don't expect perfection out of anything, but if the color is uneven I do usually pass. If it is graded even I assume it is either the cut, clarity (like a cloud) or even just the lighting/how the picture it taken that has it looking otherwise.

 

[yssie]

That's an excellent topic Kenny,

Even and uneven are the way the color distributes on the stone, in case the color isn't distributed equally along the stone, it will be graded as uneven,
Uneven are more likely to be found in the following shapes: Emerald, Baguettes, Princess cut and Briolette.
I'm enclosing a pic of 0.12ct FBG Baguette we used to own, you can see the center part of the stone doesn't have the same color like the sides, and indeed GIA graded this stone as uneven

Due to the cut of this shapes it's more possible the color will be distributed unevenly in the stone.

Bow tie you see in Pear shape, Marquise and Oval isn't uneven color, since it is part of the cut of the stone..
It also possible if the stone has a cloud on certain point or a color patch and it causes an unequal color distribution.

Not applicable is like anonymous said, for stones that are below Fancy in Grade(between Faint and Fancy Light.

Best

Itzik Polnauer

Hi Itzik,

Hope you don't mind if I ask a few more questions. I am a bit confused reading your answer: that "uneven" is more prevalent in certain shapes (ECs, baguettes, princesses..) seems to indicate that cut type to form a certain shape plays a part in this determination. It also indicates that even/uneven is determined by what the grader sees face-up in the cut stone, not in the rough itself, like grading fancy colour light vs. vivid depends on what is seen face-up. So why is even vs uneven not considered in shapes like pears, marquises, where the face-up colour does seem to vary quite a bit because of the cut type even if the rough is clearly evenly coloured (I'm thinking of the baguette examples, where cut type seems to be the reason for the uneven colour distribution much like bowtie/concentration at tip of pears)?

 

[tyty333]

This one was graded Not Applicable.
What the heck does that mean?

Just means its so darn cute the distribution doesnt matter

 

[dkodner]

Working from pictures, it is almost impossible to really tell why one stone got uneven, and another did not. Kenny, as you know, holding them face up in a grading tray is completely different then what you can make a colored diamond look like in a picture.

This is an area where there are certain criteria the GIA is following to determine the even/uneven status, but I cannot say I fully understand their thought process all of the time. I see many contradictions. That being said, almost always the distribution is essentially grading the cut of the diamond. There are some instances where the diamond is actually color zoned (like in a colored gemstone), but those are not common. The distribution is graded separately from color itself. They place the stone face up in a grading tray, tilt it back and forth and assign an even/uneven grade. It gets muddy when you consider fancy shapes.

I'll use Kennys' pear shape violet as an example. You can see how the cutting style is leaving the top shoulders of the pear light. You could look at that picture and make the assumption it is uneven. But what they are looking at is if the color is even throughout the parts of the stone that show color. With a "bow tie" effect in most fancy cuts, if they did not do it this way, every one of them would be graded as uneven. They will however consider how the color looks within the areas that are showing color. So the baguette that Itzik showed us, is uneven most likely because on one end of the baguette it is darker than on the other end of the baguette. They are not looking for saturation throughout the stone, that is a common misunderstanding. Saturation is graded completely separate from distribution.

So Yssie, your assumptions are correct. Has nothing to do with the rough. It is graded face-up with the graders eyes, and you could indeed have an even distributed piece of rough that after cutting gets an uneven grade from the GIA.

I hope that helps....

 

[yssie]

Thank you for your input dkodner!


I am an outsider in this thread as I know very little about FCDs and have none myself (yet ).

If I can threadjack for a sec to make sure I'm following:

Hue = colour (green/blue/pink). GIA defines 27 distinct colours w/ 7 primary colours (red, orange, yellow, green, blue, violet, purple). Modifiers may lower or increase the value of the stone depending on what colour we are talking about and what the modifiers are. A brown pink will have a more strong brown colour than a brownish pink, and a brown pink will be worth more than a pink brown.
The colour of the stone is an inherent part of the rough - can't be altered by cut/shape.

Tone = darkness of the Colour (light vs dark). Also is an inherent part of the rough and can't be altered by cut type.

Saturation = strength of whatever Colour of whatever Tone is present. This is something cutters can alter by cutting to maximize path length, and is graded face-up. The actual strength of a given saturation denomination depends on the colour - a Fancy yellow may have more strength of colour (saturation) than a fancy blue.

Tone and Saturation are somewhat interdependent - Faint/Very Light/Light/Fancy Light/Fancy/Fancy Dark/Fancy Deep/Fancy Intense/Fancy Vivid. Certain Colours (red & brown were discussed in another thread earlier this week) may not be assigned certain tone/saturation denominations. I found this chart:


Evenness refers to the distribution of whatever Colour of whatever Tone in whatever Saturation throughout the faceted gem. It is also a function of cut type, and is also graded face-up.
Q - is "evenness" an evaluation of just Colour in the portions of the stone that are showing colour? Or does it consider Tone and Saturation as well?

 

[dkodner]

Q - is "evenness" an evaluation of just Colour in the portions of the stone that are showing colour? Or does it consider Tone and Saturation as well?

Yssie- You got it. I could not say it better, it's the evenness of the colored portions. Tone and Saturation are graded completely separately.

 

[kenny]

David, could tone be thought of as how an FCD would look (from light to dark) on a Black and White TV?

For you young people, Black and White TV sets were what us old farts had as kids.

 

[yssie]

Ahh - thanks again dkodner - and kenny for starting yet another helpful thread

 

[kenny]

Yssie, sounds like you're thinking of taking the FCD plunge.
Do you have some color/shape/size in mind?

Just nosey.

 

[yssie]

Yssie, sounds like you're thinking of taking the FCD plunge.
Do you have some color/shape/size in mind?

Just nosey.

haha no, more's the pity! I'd love a very light peachy (so orangy pink?) heart or pear - I'll bezel it in RG and make a bracelet - but that's a whilst away I'm afraid!

My first order of business is octavia studs


Not that I wouldn't LOVE a day with your collection IRL (::hint:: ::how's that video coming:: )

 

[kenny]

Yssie, sounds like you're thinking of taking the FCD plunge.
Do you have some color/shape/size in mind?
Just nosey.

haha no, more's the pity! I'd love a very light peachy (so orangy pink?) heart or pear - I'll bezel it in RG and make a bracelet - but that's a whilst away I'm afraid!
My first order of business is octavia studs
Not that I wouldn't LOVE a day with your collection IRL (::hint:: ::how's that video coming:: )

Octavia studs would be Killer!

I actually tried videotaping FCDs today.
The lens seems to focus farily closely, but knowing when it is in focus on that tiny cheapo screen is not easy.
I have to download it to the puter.
THen I learned how to record directly onto iMovie on my Mac, but the lighting I used sux, and I have to figure out how to use iMovie.

Some FCDs just came out dark with no color.
Then I tried putting FCDs on a folded piece of watercolor paper that I painted gray; this seemed to help the exposure more than the FCDs being on white salt.

Still experimenting.

 

[slg47]

Yssie, sounds like you're thinking of taking the FCD plunge.
Do you have some color/shape/size in mind?

Just nosey.

haha no, more's the pity! I'd love a very light peachy (so orangy pink?) heart or pear - I'll bezel it in RG and make a bracelet - but that's a whilst away I'm afraid!

My first order of business is octavia studs


Not that I wouldn't LOVE a day with your collection IRL (::hint:: ::how's that video coming:: )

can we expect to see these studs sometime soon???

 

[yssie]

Kenny - maybe a grey card w/ the right reflective surface? I'm seriously excited to hear you're trying! Can't wait to see when you do nail it


slg - oh I may have understated the little while part - DH would fry me if I dropped that sort of money right now give him a year to get used to the idea..

 

[Tom Gelb]

what dkodner wrote is for the most part very much correct. However the following is not quite right "But what they are looking at is if the color is even throughout the parts of the stone that show color. With a "bow tie" effect in most fancy cuts, if they did not do it this way, every one of them would be graded as uneven." The evenness of a color as defined by GIA is not about how similar the color is where it is visible (if that is what Mr. Kodner is meaning), rather it is a function of how much of the diamond shows color versus absence of color (i.e. extinction, brilliance, etc.) when viewed face up. If a diamond shows color over 50% or more of the crown then it would be graded as even, if less than 50% it would be graded as uneven. To continue with the pear shape example, if the bow tie (which would be defined as absent of color) were quite large and more than 50% of the crown when viewed face up, then it would have been graded as uneven. Similarly for the baguette, since the color is only at the heads and the majority of the diamond shows no color it was graded as uneven.
If anyone needs more clarity I would be happy to respond.
I hope this helps.

 

[kenny]

Thanks Thomas.

Do you agree with GIA's color distribution grade on all the examples I posted above?
Do you feel this is a spec where there are more examples of GIA not following its own rules?

 

[yssie]

what dkodner wrote is for the most part very much correct. However the following is not quite right "But what they are looking at is if the color is even throughout the parts of the stone that show color. With a "bow tie" effect in most fancy cuts, if they did not do it this way, every one of them would be graded as uneven." The evenness of a color as defined by GIA is not about how similar the color is where it is visible (if that is what Mr. Kodner is meaning), rather it is a function of how much of the diamond shows color versus absence of color (i.e. extinction, brilliance, etc.) when viewed face up. If a diamond shows color over 50% or more of the crown then it would be graded as even, if less than 50% it would be graded as uneven. To continue with the pear shape example, if the bow tie (which would be defined as absent of color) were quite large and more than 50% of the crown when viewed face up, then it would have been graded as uneven. Similarly for the baguette, since the color is only at the heads and the majority of the diamond shows no color it was graded as uneven.
If anyone needs more clarity I would be happy to respond.
I hope this helps.

Huh.

So it sounds like it's not actually a measure of distribution at all (as in, it doesn't consider the location of the colour throughout the stone), just a binary > or < 50% visible colour *somewhere* as seen face-up.

Which explains why a pear that looks clearly more coloured at the tip may get an "even" grade, because more than 50% of what we see face-up is showing colour - doesn't matter where it's showing that colour (that it's all on one side of the stone and not on the other).

Am I understanding properly?

 

[dkodner]

Hi Tom,

I appreciate your correction. I was under the impression it was the evenness of color in the colored sections, not how much of the color was visible in relation to the rest of the stone. I understand much better now. Thank you for the clarification. Old dogs can still learn...