Test your eye for color in diamonds- and EGL's

[Rockdiamond]

All three stones graded E color.
Can you see the difference?

 

[JaneSmith]

On my iDevice the EGL looks yellowish like an I, and the middle GIA one looks whitest. Are they all the same cut? Fluor?

 

[04diamond<3]

All three stones graded E color.
Can you see the difference?

Yes. That's pretty obvious. That's EGL Isreal. Mine is EGL USA and I have an F color stone that was just graded by GIA as an F color stone. Also, the GIA color stone on the right is not the same as the middle GIA stone.

 

[Snicklefritz]

Agree with JS on all points.

 

[Rockdiamond]

The stone on the far right has strong Blue Fluorescence- and certainly does show a difference through the pavilion on my monitor, as in real life.
The stone on the far right is a Pear, the other two stones are Cushion Modified Brilliant Cut

Re diamonds that have EGL reports.
Nothing personal intended- my point has nothing to do with the diamonds themselves- rather the grades issued to the diamonds.
EGL USA has a much better reputation than EGL Israel in this regard- yet it's still a fair statement to say that the trade will not place the same credibility on EGL USA that is given to GIA- or anywhere near it.

 

[denverappraiser]

There was a wonderful quote from Martin Rapaport on this:
"I have no problem with the ham sandwich. My problem is with the guy who calls it kosher."

 

[webdiva]

There was a wonderful quote from Martin Rapaport on this:
"I have no problem with the ham sandwich. My problem is with the guy who calls it kosher."

That's awesome!

 

[TC1987]

Now I have a question. How much does "mass" of the diamond affect the perceived color? Say if you had there, side by side, three RBs and they were 2ct, 1.5ct and 1ct, all correctly graded "E," would the larger one appear to be a different color (less white) than the 1ct? Or are they all the same tint, and only the size would look different?

 

[SB621]

There was a wonderful quote from Martin Rapaport on this:
"I have no problem with the ham sandwich. My problem is with the guy who calls it kosher."

That might be my new signature for PS!

 

[OCgirl]

Wow this is so interetsing. I love this!!! Thank you for posting this.
Can you post more?!??

 

[echomomm]

Now I have a question. How much does "mass" of the diamond affect the perceived color? Say if you had there, side by side, three RBs and they were 2ct, 1.5ct and 1ct, all correctly graded "E," would the larger one appear to be a different color (less white) than the 1ct? Or are they all the same tint, and only the size would look different?

This is my question, too. I don't know the answer, but it often seems that colour is magnified in a larger stone.

 

[yssie]

Now I have a question. How much does "mass" of the diamond affect the perceived color? Say if you had there, side by side, three RBs and they were 2ct, 1.5ct and 1ct, all correctly graded "E," would the larger one appear to be a different color (less white) than the 1ct? Or are they all the same tint, and only the size would look different?

This is my question, too. I don't know the answer, but it often seems that colour is magnified in a larger stone.

My understanding is that colour grading is done "as if a chip is knocked off the stone" - so the colour of the hypothetical chip would determine the colour grade, not the colour face-up and not the apparent body colour of the stone as a whole from the side or underside (which is definitely affected by volume - more layers of coloured material to concentrate colour in a bigger stone).

How on earth they visualize these hypothetical chips without letting stone size and apparent body colour affect them... I don't know! But it's a subjective thing. And then there's also the possibility of re-submitting a stone if you're unhappy with the grading, at which point there's also the chance that the grading is changed to something more favourable...

One of the appraisers who posts on here once told us a bit about his master set - apparently those stones are graded differently, and he had one that was right in the middle of two colours so it was easier to decide if the stone was the higher or lower colour because the only question was whether it had more or less tint than the master, vs. trying to figure out if a stone is at the lower or upper range of a given grade. I'll see if I can dig it up - I can't remember *who*, which would help!

It's an interesting question - I hope one of our tradepeople will chime in with more info. I do remember David's article talking about how FCDs are graded face-up, and how re-cutting a stone can have a huge impact on what colour grade it earns and how much it can be sold for.

 

[Rockdiamond]

Yes I will gladly post more shots Monday
I'll get a shot of different size stones same color

 

[Rockdiamond]

Now I have a question. How much does "mass" of the diamond affect the perceived color? Say if you had there, side by side, three RBs and they were 2ct, 1.5ct and 1ct, all correctly graded "E," would the larger one appear to be a different color (less white) than the 1ct? Or are they all the same tint, and only the size would look different?

This is my question, too. I don't know the answer, but it often seems that colour is magnified in a larger stone.

My understanding is that colour grading is done "as if a chip is knocked off the stone" - so the colour of the hypothetical chip would determine the colour grade, not the colour face-up and not the apparent body colour of the stone as a whole from the side or underside (which is definitely affected by volume - more layers of coloured material to concentrate colour in a bigger stone).

How on earth they visualize these hypothetical chips without letting stone size and apparent body colour affect them... I don't know! But it's a subjective thing. And then there's also the possibility of re-submitting a stone if you're unhappy with the grading, at which point there's also the chance that the grading is changed to something more favourable...

One of the appraisers who posts on here once told us a bit about his master set - apparently those stones are graded differently, and he had one that was right in the middle of two colours so it was easier to decide if the stone was the higher or lower colour because the only question was whether it had more or less tint than the master, vs. trying to figure out if a stone is at the lower or upper range of a given grade. I'll see if I can dig it up - I can't remember *who*, which would help!

It's an interesting question - I hope one of our tradepeople will chime in with more info. I do remember David's article talking about how FCDs are graded face-up, and how re-cutting a stone can have a huge impact on what colour grade it earns and how much it can be sold for.

In my experience stone size does not change the basic methodology of color grading.
In general diamonds have consistent color throughout the stone- although this is not always the case.

 

[oldminer]

The mass of a diamond has an effect on color grading. Diamonds are graded "as if a chip off the stone" was the graded object. Nothing else in the world is color graded that way, BUT nothing else in the world is so valuable based on hair-splitting color grading, either. There would almost never be a large D or E color diamond if the body color sample method was not used. Please take a moment to think how colorless glass made into a large table top appears green when viewed through the edge, through the long length of the glass. Yet, the glass has next to no color when viewed through the top, flat surface to the opposite side. It is the mass of material in the long direction absorbing and refracting light away from transmitting it to your eye causing that green darker color as the glass is all one color.

The success of GIA and other labs is partly in following a unique convention of grading color in the way they do. Other graders have the difficult task of understanding how 0.25ct diamonds are graded and then the rest of their life to understand how 1.00ct, 2.00ct and20ct diamonds are color graded with what looks like different color standards. The appraiser/grader has to learn from experience and comparison how the GIA Lab actually does their grading, as they only teach the subject based on small diamonds to their students.

I appreciate Rockdiamonds photos. The EGL Israel is indeed a fine example of a kosher ham sandwich. However, the color grading of most pear and other fancy shapes is best done somewhat diagonally to avoid adding concentrations of color associated with the pointed end of some cuts. We tend to meet GIA grading with princess cuts by grading through the stone about 20 degrees off the pointed corner and avoiding the corner color concentrations. Ultimately, it appears that most diamonds are color graded from the perspective of their best color through the side view and often some adjustment based on face-up in a final analysis. Only the GIA lab knows the exact methodology used and likely it has undergone several tweeks and changes since the 1950's. Surely the GIA grading of color system has been adjusted more than once in the past ten years.

Color grading using GIA blessed master sample diamonds is a weak link in all grading done by anyone outside the GIA lab. If EGL, IGI, or AGS were to offer master diamond set grading to their lab's standards, we'd find surprising nuance differences, and maybe more. This isn't a criticism of those labs and they are not all the same, for sure. However, the color grading standards in wide use do have issues which a simple photo often can demonstrate. I think that is why most professionals here encourage GIA reports for their color and clarity grading although we also encourage AGSL reports for their cut quality analysis. It may not be a simple solution, but it is how many professionals see the grading situation in its current form.

 

[TC1987]

^ Fascinating! I thought it had to be done something like that. Thanks, Oldminer.

 

[Rockdiamond]

I have a different experience than Old Miner in this regard.
Of course an appraiser, and a dealer have completely different outlooks- and methodology.
I need to look at , and grade, diamonds for the purpose of purchase. I can't take the time a good appraiser will take on any given stone, because I have to grade too many if I'm going through parcels without GIA reports. Plus, if I make a mistake, it's coming out of my pocket.
Point is, dealers have to develop practical means of quickly grading color or go out of business.
I look at a diamond- no matter the size- and I see the color.
I am lucky in that I have the ability to see the subtle shades and color memory.
Some people are far less sensitive to color.
People who are sensitive to color can be trained. But if they are not, this is not something that can be taught.
We also agree that the report is the final arbiter.
No one will have a 100% correct rate with GIA or AGSL.
Sometimes it just goes the other way.

In some senses a larger stone is easier- as there's more mass- on the other hand, if you're sorting through melee for color- it's pretty easy to pick out darker stones- of course that' a different activity than color grading.
Glass has entirely different properties than diamond in this regard- at least in the quantities we're talking about.
To my eye, a 5ct D color is as colorless as a .05ct D color. This is why we love diamonds a lot more than glass. I cant really imagine a diamond the size and shape of a plate glass window- but we can look at small pieces of glass- which are not nearly as clear as a diamond.

As far as the "chip" method:
Unless we actually chip off a piece of diamond, there's no way not to look at the entire stone.
Same for fancy shapes- generally, they lay most easily in a certain direction on their tables- you're not realistically going to try and grade a marquise by the point because it is hard to look through it that way.
I would suggest looking at the diamond from as many angles as possible- but for calibration, table down on white paper straight on, not diagonal.
Again everyone has their own methods, but this has worked well for me- and when I've taught people it's the methodology I've taught.
I will make sure to get a few diamonds of drastically different sizes- same color and shape to photograph for demonstration.