Why no CA/PA angles on fancy colored diamonds?

[lovedogs]

Probably a silly question, but I couldn't find anything on the PS search engine or google searching.

Why doesn't GIA give any info about CA or PA for fancy colored stones? Does it have to do with performance differences for these colors, or something else I'm missing?

 

[bludiva]

i think it's because they're often cut to hold in as much color as possible as opposed to cutting for light return. hopefully some experts will chime in.

AGS has a new report for fancy colors that goes into more detail.

https://cdn.ymaws.com/www.americang...rowndiamonds/AGSL_CDD_Modified_Color_term.pdf

 

[lovedogs]

i think it's because they're often cut to hold in as much color as possible as opposed to cutting for light return. hopefully some experts will chime in.

AGS has a new report for fancy colors that goes into more detail.

https://cdn.ymaws.com/www.americang...rowndiamonds/AGSL_CDD_Modified_Color_term.pdf

I wish everywhere had these for the FCDs! It's been driving me crazy that all I can see is table/depth and nothing else. This document is very helpful!

 

[Karl_K]

They are cut different than colorless diamonds.
What matters is the face up color and how even the color in the stone appears.
Even clarity is not a big factor unless it is super clean or has visible inclusions that interfere with the color.
AGS is trying to get in the game with browns with their new colored diamond report but it remains to be seen if it will be widely accepted.
Notice there is not an ASET image on the AGS color report.

 

[lovedogs]

Thank you @Karl_K ! This makes me think that I need to stick with lower colors (L/M/N, etc) with the "slight brown" note on the GIA report. That way I can check all angles and figure out performance and ALSO get the slight brown I love. It's helpful to understand how FCDs are considered different than the other D-Z colors.

 

[Rockdiamond]

From my perspective- colorless RBC cut assessment is completely different from FCD cut assessment.
In fact, RBC assessment is completely different than fancy shape assessment in general.
Based on countless discussions with consumers, I find that there's a chasm of misunderstanding based on trying to use methods designed for colorless round diamonds ( ASET/IS, etc), on other shaped, and colors.
If you look at the finest round Fancy Intense Yellow Diamonds ( for example) they are going to have aspects we'd toss a colorless round for- thick girdle- steep crown, etc.
An argument could be made that we're too strict on colorless rounds- but that's another story.
So, adding CA/PA on FCD reports might further cloud the issue for consumers.
As Karl points out- clarity is another factor judged differently in round diamonds.
I can also attest to the fact that many consumers know enough about clarity to be dangerous- to themselves!
It's not always true that more information is better.

 

[WinkHPD]

An argument could be made that we're too strict on colorless rounds- but that's another story.

A much better and more factual argument can be made that we are nowhere near strict enough on colorless rounds. Far too many examples of absolute garbage cut simply to retain weight, beauty be darned...

Wink

 

[HDer]

Thank you @Karl_K ! This makes me think that I need to stick with lower colors (L/M/N, etc) with the "slight brown" note on the GIA report. That way I can check all angles and figure out performance and ALSO get the slight brown I love. It's helpful to understand how FCDs are considered different than the other D-Z colors.

If you're looking to actually get a brown diamond I'd recommend looking for an even lower color than L or M. A well cut L or M "faint brown" diamond can show very little color from the top, where you'll be looking at it most of the time.

I've read some people say that this is because brown is a color that we're less sensitive to. I've read other people who say that the difference between the side view (where the color is graded) color and the top view color in a brown diamond is larger than for a yellow one. I've further read some people write that GIA purposely grades brown diamonds a couple of color grades lower.

Whatever the reason, I can tell you from personal experience that a L diamond, faint brown, can look completely white from the top.

 

[Rockdiamond]

Wink- true, I should have been more specific. A lot of what’s written online can lead people to believe if they don’t buy super Ideal they’re going to get some sort of defective diamond. Sure there’s plenty of badly cut diamonds out there. But it’s possoble for some readers to feel the need to eliminate many stones that ARE well cut based on very subtle aspects.
Not everyone prefers the look of a super ideal.
That is a fact

 

[Rockdiamond]

Thank you @Karl_K ! This makes me think that I need to stick with lower colors (L/M/N, etc) with the "slight brown" note on the GIA report. That way I can check all angles and figure out performance and ALSO get the slight brown I love. It's helpful to understand how FCDs are considered different than the other D-Z colors.

I'm a lover of "blush" sort of stones.
We've seen faint brown stones that actually look a bit pink.
But in general- using a formula designed to get maximum white light out of the top of the diamond will not produce this effect.

Whatever the reason, I can tell you from personal experience that a L diamond, faint brown, can look completely white from the top.

When a RBC is super well cut ( based on colorless standards), and light brown, this is generally the result. Which is a plus for people looking for colorless- because brown saves money.
But if one is looking to actually see the color, it might be wise to throw out many of the rules we use judging colorless.
For example: depth. A colorless RBC of 65% depth? FUGHETABOUTIT!!!
But an RBC with a tinge of brown may look amazing at 65% depth.
Same with girdle thickness. A thick girdle will eliminate a G color- but in a K-L with brown, it can be an asset for projecting color out of the stone.
I've seen such stones- they did give up spread from the additional depth- but they were still brilliant and sparkly.

 

[Texas Leaguer]

Lovedogs,
Others have already explained why specific angles and proportion factors are not particularly helpful to fancy color evaluation, and parameters appropriate for colorless diamonds might actually be detrimental to face up appearance of colored diamonds.

Diamond cutting is a mixture of art and science. With Fancy Color it's heavy on the art!

 

[OoohShiny]

Thank you to all the Pros for a great range of discussion points in this thread!

 

[lovedogs]

Thanks to all for making this more clear--appreciate all the info!