Trying to wrap my head around grading reports

[bonesy]

Hello,

So I am trying to wrap my head around grading reports and what this means for a diamond that would be purchased online.

1. Through my research I understand that GIA is the gold standard.
2. That AGS is more strict and the diamond may be 1 color & clarity better than cert vs. GIA.
3. That EGL USA is more liberal and the diamond may be 1 color & 2 clarity below that of a GIA cert

So what does this mean in terms inter-cert comparison? Say if I have these three stones:

1. EGL-USA -- 1.33c D SI3 very good -- 3600
2. AGS -- 1.05c H SI2 very good -- 4500
3. GIA -- 1.08c G SI1 Excellent -- 4400

Would it be correct to compare them as:

1. Carat = 1 > 3 > 2
2. Color = 1 > 2 = 3
Effectively scaled to GIA standard -- 1. F, 2. G, 3. G
3. Clarity = 2 = 3 > 1
Effectively scaled to GIA standard -- 1. I2, 2. S1, 3. S1
4. Cut = 3 > 1 = 2

Thus if considering that a GIA 1.25 F I2 Very good = 5800; would the EGL-USA diamond be a better value?

The future Mrs. says she would like size, but I just could not be happy with myself if I was to give her a diamond that I see as yellow or with visible inclusions. The budget is $5000 +/- 500. Therefore I have been looking at GIA/AGS cert 1.0-1.1c/F-H/SI2 but I keep running into these IGI or EGL cert diamonds that are bigger and better classified even if I adjust them to GIA standards and better fit the budget.

So I am asking for your thoughts/experience with EGL cert diamonds -- how trustworthy is the cert? is the scaling and price comparison reasonable? is there something that I am just missing?

Thanks for your help.

 

[JulieN]

an I2? please don't. I1 is the absolute cutoff, and even then it will have visible inclusions.

Your carat comparison is not useful, the cut has a large impact on how big it looks.

 

[distracts]

The only one I'd consider there is the GIA Excellent.

 

[denverappraiser]

Yes, you are missing something. The stone did not come out of the ground with a lab brand. Someone, usually the cutter, chose which lab to use. They were probably diamond experts themselves, they had access to every lab in the world, they probably have an account at every one of them, they cost roughly the same, and they picked EGL. Why?

(hint: It's about the money)

 

[John P]

Bonesy: It would be nice if your "inter-cert" comparison chart were viable. But it's not possible; for several reasons:

1. The inconsistencies between EGL and GIA are not consistent. Some are close. I've seen others differ by up to 7 grades.
2. Color and Clarity grades are not static, they occur on a sliding scale. One J color may be closer to I, another closer to K.
3. A grading report doesn't come close to revealing every piece of information about a diamond.
4. Don't get me started about cut grading; the labs don't even take the same fundamental approach and a single cut grade (for any lab) encompasses far more visible width than color and clarity subdivisions...each needs to be considered on its own merits.

RE the premise of your post: Here are six diamonds offered currently on one of our private Business-to-Business platforms.

1.01 D VS2 EGL Excellent "H&A"
1.01 H VS2 AGS Ideal
1.01 H VS2 GIA Excellent
1.01 F SI1 AGS Ideal
1.01 G SI1 GIA Excellent
1.01 E VS1 EGL Excellent "H&A"

What is interesting about these six is that all of them are priced within $150 of each other to the trade.
How can that be? ...

Because while we don't have "inter-cert" formulas, pros know what a diamond is worth. It's pretty reliable that the 1.01 D color (above) will actually be far closer to the GIA G/H colors in that price range. But other factors are at play too. I'll elaborate...

Listed from least to most expensive:

>Least expensive: The 1.01 D VS2 EGL "H&A" - it is clearly not D and maybe not VS2. The HCA is 4.6 (fwiw) with a PA of 41.4
> For 30$ more: The 1.01 H VS2 AGS Ideal - sounds accurate. HCA 1.8. Platinum report shows small indexing issues but a nice cut.
> Add another 60$: The 1.01 H VS2 GIA Excellent - also sounds accurate. HCA 1.4. No way to see true light performance.
> Add another 8$: The 1.01 F SI1 AGS Ideal - possibly soft F (?) but the angles are what kill it. 57/41.7/33.3 is a terrible AGS0. The platinum report shows multiple inconsistencies in brillianteering. The HCA is 5.1 (for an AGS0...bummer).
> Add another 50$: The 1.01 G SI1 GIA Excellent - this appears to be a strong SI1, possibly soft/border G. VG symmetry raises questions for me. No way to see true light performance. HCA is 1.6.
> And for another 10$: The 1.01 E VS1 EGL "H&A," - which is clearly not E nor VS1 (grouped in with these others) but may be G-H/VS2-SI1. No way to know without examining it in person. HCA is 5.1 with a steep PA.

Understanding a jeweler will pay close-to the same price for any of these diamonds... Which do you suppose has the most appeal to a consumer who has only done little or no research? How could professionals take advantage of that?

(I saved the grading reports but didn't upload them here - if anyone is interested in seeing them I can do that tomorrow).

Cheers,

 

[madelise]

Bonesy: It would be nice if your "inter-cert" comparison chart were viable. But it's not possible; for several reasons:

1. The inconsistencies between EGL and GIA are not consistent. Some are close. I've seen others differ by up to 7 grades.
2. Color and Clarity grades are not static, they occur on a sliding scale. One J color may be closer to I, another closer to K.
3. A grading report doesn't come close to revealing every piece of information about a diamond.
4. Don't get me started about cut grading; the labs don't even take the same fundamental approach and a single cut grade (for any lab) encompasses far more visible width than color and clarity subdivisions...each needs to be considered on its own merits.

RE the premise of your post: Here are six diamonds offered currently on one of our private Business-to-Business platforms.

1.01 D VS2 EGL Excellent "H&A"
1.01 H VS2 AGS Ideal
1.01 H VS2 GIA Excellent
1.01 F SI1 AGS Ideal
1.01 G SI1 GIA Excellent
1.01 E VS1 EGL Excellent "H&A"

What is interesting about these six is that all of them are priced within $150 of each other to the trade.
How can that be? ...

Because while we don't have "inter-cert" formulas, pros know what a diamond is worth. It's pretty reliable that the 1.01 D color (above) will actually be far closer to the GIA G/H colors in that price range. But other factors are at play too. I'll elaborate...

Listed from least to most expensive:

>Least expensive: The 1.01 D VS2 EGL "H&A" - it is clearly not D and maybe not VS2. The HCA is 4.6 (fwiw) with a PA of 41.4
> For 30$ more: The 1.01 H VS2 AGS Ideal - sounds accurate. HCA 1.8. Platinum report shows small indexing issues but a nice cut.
> Add another 60$: The 1.01 H VS2 GIA Excellent - also sounds accurate. HCA 1.4. No way to see true light performance.
> Add another 8$: The 1.01 F SI1 AGS Ideal - possibly soft F (?) but the angles are what kill it. 57/41.7/33.3 is a terrible AGS0. The platinum report shows multiple inconsistencies in brillianteering. The HCA is 5.1 (for an AGS0...bummer).
> Add another 50$: The 1.01 G SI1 GIA Excellent - this appears to be a strong SI1, possibly soft/border G. VG symmetry raises questions for me. No way to see true light performance. HCA is 1.6.
> And for another 10$: The 1.01 E VS1 EGL "H&A," - which is clearly not E nor VS1 (grouped in with these others) but may be G-H/VS2-SI1. No way to know without examining it in person. HCA is 5.1 with a steep PA.

Understanding a jeweler will pay close-to the same price for any of these diamonds... Which do you suppose has the most appeal to a consumer who has only done little or no research? How could professionals take advantage of that?

(I saved the grading reports but didn't upload them here - if anyone is interested in seeing them I can do that tomorrow).

Cheers,

Thanks for this post. Geez, up to 7 grades off? That's so scary.

 

[John P]

Thanks for this post. Geez, up to 7 grades off? That's so scary.

For certain. Especially for a consumer who bases a purchase decision on the idea that the range of deviation is consistent. It's simply not.

There are traders in the world's diamond centers who use the known-inconsistency to cull-through reputedly soft reports and corresponding stones, seeking hidden gems that are deeply discounted to the trade but maybe not as "off" in color/clarity/cut/other as the discount would reflect.

I was in NYC last month and sat with a colleague as he brought in numerous diamond from a supplier across the street, with such a goal. The idea was to purchase a soft-graded stone at a huge discount, recut-improve it to top cut standards and grade it at AGS or GIA for final sale. I've been involved in this before and in some cases it might be practical, but those cases are very far-between... Diamond manufacturers and suppliers are very smart people. We brought in quite a few stones and when the discount was crazy-big there was something about the diamond (color, clarity or something not even on the report) which was correspondingly crazy-off.

This lends itself to the axiom: If it seems too good to be true it probably is.