Colour grading (D-Z)

[yssie]

I had some questions about colour grading from another thread and called GIA to have a gemologist clarify. I thought others might be interested in the responses too

My original (wrong) understanding:

Someone please correct me if I'm mistaken, but I believe D-J can be many colours. I remember an old poster PQCollectibles posted about a "blue J" from BG when he was w/ WF. My understanding is that a "blue J" will have comparatively less actual body colour than a "yellow J" - the scale for colours other than yellow/brown is narrower, and more than a minute amount of colour is enough to push a blue or a pink past the D-J range into Fancy territory.

ETA:
[URL='https://www.pricescope.com/community/threads/j-color-in-very-open-setting.15833/']https://www.pricescope.com/community/threads/j-color-in-very-open-setting.15833/[/URL]
and grey is mentioned in this one too [URL='https://www.pricescope.com/community/threads/how-common-are-colors-other-than-yellow-in-g-k-diamonds.15824/']https://www.pricescope.com/community/threads/how-common-are-colors-other-than-yellow-in-g-k-diamonds.15824/[/URL]

The questions:

--GIA will call a stone with *yellow* body colour of certain strength/saturation (let's call this "X") a K.
--GIA will call a stone with *brown* body colour of certain strength/saturation >= "X" a K, and will note that colour is due to brown on the report.
--GIA will call a stone with *yellow* body colour of strenght/saturation --GIA will call a stone with *brown* body colour of strength/saturation --If the stone is cut from *pink* rough, it is either a D (completely colourless) or a Faint, Very Light, Light, Fancy, Fancy Intense, Fancy Vivid, Fancy Deep. There is no possibility of acquiring a "blue GIA J".
As in, diamonds with hints of any colour other than yellow or brown will NOT be assigned a letter from E-J. If they are completely colourless they are Ds, if they have even an inkling of a colour other than yellow or brown they go straight to the Faint/Light/etc. scale (which changes depending on the specific colour).


And the answers:

--GIA will add a brown notation if warranted from J or below. A G wouldn't ever get a grown notation.
--There's no such thing as a pink or blue G or J. It's either a D, a yellow/brown E-Z, or it's re-routed for a coloured diamond report and given a worded description.

 

[acebruin]

thanks for clarifying Yssie... i've always thought anything from D-H wouldn't get any brown notation, just because of the nature of the grade... near colorless...

 

[Blue-Seeker]

Very interesting. Although GIA does not note body color in colorless and near colorless diamonds, that doesn't mean the body color is not visible to some customers. Perhaps I am very, very color-sensitive, more than most people, but I can easily see body color in diamonds. I own a J that has a brown tint, and it is a very pretty diamond. It is an AGS 0 diamond that I took to be independently appraised by a local appraiser. She started out with her master stones and then said she was going to get out her "brownies" because she could not get a good match with her standard master stones. She is the one that pointed out the brown in the stone to me. She showed me how her J "yellow" master stone was not at all close to the color of my diamond. I don't know about blue or pink body color, because I haven't seen anything like that in person. But I have seen diamonds with a grey or silver body color.

 

[yssie]

It is interesting Blue - easy to forget amidst all the numbers and letters and percentages that the colour grading is done by eye, by humans, and so some variance and disagreements are to be expected!

 

[MeganR]

I took this from my GIA diamond grading lab manual...

Brown diamonds in the normal color range are fairly common. THere are some differences between the way you describe brown stones darker than K in the normal range and the way you describe yellow stones in that range. Describe brown diamonds darker than K with the letter grade followed by a fancy-colored diamond grade: Faint brown for K to M, Very Light brown for N to R, and Light brown for S to Z. FOr example, you'd grade an N-grade brown diamond as N-Very Light brown.

Gray diamonds with color that's equal to or greater than K are graded using the fancy-color system.

All diamond color grades are determined based on depth of color.

And yes, diamond grading is subjectively graded by the eye, but there are strict standards in place to ensure accuracy. For example, color graders only grade color for one hour per day!


Blue-Seeker - I agree wholeheartedly with your appraiser. I hate trying to get an accurate color grade on a diamond with brown body color using a standard master set. It's a total pain!

 

[yssie]

A big *thank you* to Tom Gelb for answering my questions so clearly!

Hello Yssie,

I believe I can shed a little more light here. I worked in fancy colors at the GIA for a number of years. Please note the responses in red below. If you have anymore questions please let me know.

All the best,

Tom

No, I'm definitely not talking about fluor - only the body colour of the stone. So am I understanding correctly (w/ reference to GIA's grading only):

1. GIA will call a stone with *yellow* body colour of certain strength/saturation (let's call this "X") a K. Correct
2. GIA will call a stone with *brown* body colour of certain strength/saturation >= "X" a K, and will note that colour is due to brown on the report. From K-M Faint brown, N-R Very Light Brown, S-Z Light Brown
3. GIA will call a stone with *yellow* body colour of strenght/saturation < "X" an E-J. Correct
4. GIA will call a stone with *brown* body colour of strength/saturation < "X" an E-J, but you are unsure if there will be a brown notation. No brown noted, except on internal GIA documents
5. If the stone is cut from *pink* rough, it is either a D (completely colourless) or a Faint, Very Light, Light, Fancy, Fancy Intense, Fancy Vivid, Fancy Deep. There is no possibility of acquiring a GIA G with an inkling of *pink*. Same with *blue*. If a diamond is graded D-F it will get only a letter grade regardless of the underlying tint. Remember D-F is termed "colorless" so although there may be something there it would be quite strange for a diamond to be called both colorless and blue. If a diamond has a color other than yellow brown or gray and has an equivalent color grade of G or below the diamond would then be graded in the fancy color grading scale starting with Faint.
6. We have no idea what PQCollectibles is talking about when she refers to her "steely blue J WF ACA cut from blue rough", other than that it does not in fact have an inkling of *blue*, because if it did it would be a Faint/VeryLight/Light/...
7. This quote from one of the threads linked above is also wrong: "grey diamonds are graded d-j. if there is more color than a j, it's fancy grey". Gray diamond are a strange exception and treated differently. The post is correct in that a diamond with a gray undertone would be graded on the D-Z color scale until it reached K color. At that point the diamond wold be graded on the GIA fancy color grading system starting with Faint Gray.
8. Diamonds with inklings of any colour other than yellow or brown will NOT be assigned a letter from E-J. If they are completely colourless they are Ds, if they have even an inkling of a colour other than yellow or brown they go straight to the Faint/Light/etc. scale (which changes depending on the specific colour).

I apologise to the ghosts of posters past for calling them out. There's so much info out there, much of it conflicting... I just want to understand what's really going on.

ETA: hope you don't mind the detour Kathleen!