The reason why GIA should add the SI3 grade

[flyingpig]

Wow FP - you are right - the diamond is not the stone on the cert. Good catch

Ok... after reading Garry, David, John, and Karl's comments, I am even more confused. Aren't you @yssie ??

 

[gm89uk]

Ok... after reading Garry, David, John, and Karl's comments, I am even more confused. Aren't you @yssie ??

After careful observation,I believe it is the same stone. I believe the table reflection you are seeing is a pseudotable reflection with inconsistent obstruction due to poor consistency in the pavilion mains. You can see the true table reflection (which is much larger) reflecting some blue fire. They are triangular shapes like the table reflection in the DC diagram. It is easy to mistake the blue fire to be coming from the LGF.

I think people are confusing the table reflection to be the half pavilion facets, which have been overwhelmed by the true table reflection.

 

[flyingpig]

After careful observation,I believe it is the same stone. I believe the table reflection you are seeing is a pseudotable reflection with inconsistent obstruction due to poor consistency in the pavilion mains. You can see the true table reflection (which is much larger) reflecting some blue fire. They are triangular shapes like the table reflection in the DC diagram. It is easy to mistake the blue fire to be coming from the LGF.

I think people are confusing the table reflection to be the half pavilion facets, which have been overwhelmed by the true table reflection.

Very good observation.
In my defense, these shallow and steep GOOD cut stones are much rarer than super ideal cut rounds. We just don't look at these stones alot. It has been very interesting.

 

[John P]

I love this stuff, and it wouldn't be the same without participation by you sharp observers.

After some dialogue and information sharing, @Garry and I find ourselves on opposite sides of this case. He will stand for the prosecution. I will stand for the defense . We are both rather convinced we are correct.

Therefore, your honors ~ My esteemed colleague will be presenting compelling new evidence to the court, after which I will confidently present a rebuttal.

If the truth doesn't set us free, at least we can have some fun chasing it.

(PS: There's a $5 wager on this)

 

[Karl_K]

oooohyeeeeeeeeeeeeeeeeeehhhhhhh this is going to be epic!

 

[Garry H (Cut Nut)]

Here is a photo of this diamond from the supplier, my DiamCalc modeling - I have added an extra set of facets to the draft mode. Note the pavilion reflection and angle. John, model the stone proportions in any lighting you choose then pay up
BTW the peripheral light return can never be bright with those proportions as it is with that stone.

 

[david b]

Good Morning,
I happened to check a GIA J SI2 diamond for a client lately and had the opportunity to raise this issue.

The GIA SI2 range is so big that there are diamonds that are 100% eye clean and others where the SI2 is obviously visible to the naked eye. So when thinking of a GIA SI2 you are never sure will it be eye clean or not.

One obvious solution is to ask the seller and to look at the diamond's picture.
When you see an SI2 that is too cheap-maybe this will be the reason.

See the big black inclusion near the center:

A big apology from every one!!!
I pasted the wrong J SI2 Good cut 2.07 Certificate that was on my desktop. The above certificate is NOT the one reflecting the diamond picture. It is the one below which even sharpens the case why GIA should add the SI3 grade.

 

[flyingpig]

A big apology from every one!!!
I pasted the wrong J SI2 Good cut 2.07 Certificate that was on my desktop. The above certificate is NOT the one reflecting the diamond picture. It is the one below which even sharpens the case why GIA should add the SI3 grade.

no need for apology. It has been fun.
I hope you still have your stockings. @yssie

 

[david b]

https://www.gia.edu/report-check?reportno=1209497896

 

[bmfang]

I’d prefer that GIA does not adopt the clarity nomenclature used by EGL. For a stone like that, it should have been an I1 in my books (and given the one grade +/- standard, the SI2 grade is fine, even if we question whether it should have been one).

 

[the_mother_thing]

A big apology from every one!!!
I pasted the wrong J SI2 Good cut 2.07 Certificate that was on my desktop. The above certificate is NOT the one reflecting the diamond picture. It is the one below which even sharpens the case why GIA should add the SI3 grade.

Did you see the diamond in person? Was it ‘eye clean’ and if so, to what standard (e.g. 12")?

I’m still more inclined to think that - if GIA thought it was ‘worse’ that SI2 - they’d have just graded it an I1 vs SI2. That’s why there are clarity grades below SI:

• Flawless (FL): No inclusions and no blemishes visible under 10x magnification
• Internally Flawless (IF): No inclusions and only insignificant blemishes visible under 10x magnification
• Very, Very Slightly Included (VVS1 and VVS2): Minute inclusions that range from extremely difficult (VVS1) to very difficult (VVS2) to see under 10x magnification
• Very Slightly Included (VS1 and VS2): Minor inclusions that range from difficult (VS1) to somewhat easy (VS2) to see at 10x magnification.
• Slightly Included (SI1 and SI2): Noticeable inclusions that are easy (SI1) or very easy (SI2) to see at 10x magnification
• Included (I1, I2 and I3): Inclusions that are obvious under 10x magnification – and often visible with the unaided eye – which may affect transparency and brilliance

If you saw the diamond in person and could see the inclusions unaided, I would inquire to GIA why they didn’t deem it an ‘I’ vs trying to change the grading system, which surely would create unnecessary impacts on the trade and consumers.

 

[david b]

This is a good example, you say it is a GIA SI2 but actually it is I1 so we cannot rely on the GIA grading SI2 as something consistent.

 

[the_mother_thing]

This is a good example, you say it is a GIA SI2 but actually it is I1 so we cannot rely on the GIA grading SI2 as something consistent.

I don’t understand why you suggest GIA should have an SI3 grade when they already have an I1 grade they could go with, IF that was the correct grade for this particular diamond (and I’m not suggesting it’s not the right grade - it surely looks to be worthy of being in the I-category from the pictures, but they are magnified, and we don’t see the diamond in person, so ...).

Or are you suggesting that you think GIA is ‘afraid’ or reluctant to label something an I1 for some reason? If they thought it was worse than an SI2, and they didn’t go with an already available ‘I’ grade, what makes you think they’d have gone with an SI3, if it existed in their grading system?

 

[david b]

My eye-clean definition is that you do not see any imperfection looking from table side from 20cm, this is absolutely not eye clean.
I have seen in my life GIAs SI1s that are not eye clean.
It all leads us to the knowledge that Gemology is NOT an accurate science, if one will give the same stone 3 time to GIA (without declaring it’s the same diamond)
In many times he will get more than 1 result.

 

[the_mother_thing]

My eye-clean definition is that you do not see any imperfection looking from table side from 20cm, this is absolutely not eye clean.
I have seen in my life GIAs SI1s that are not eye clean.
It all leads us to the knowledge that Gemology is NOT an accurate science, if one will give the same stone 3 time to GIA (without declaring it’s the same diamond)
In many times he will get more than 1 result.

I get it, but you’re not answering my question: If GIA is reluctant to use the I-grade for whatever reason, what makes you think they’d use SI-3 on a stone with inclusions warranting such?

 

[yssie]

I hope you still have your stockings. @yssie

Since I don’t believe I own any stockings - but am rather fond of my few hats - it was a conveniently mixed metaphor An explanation of over-obstruction wonking pav reflection and brillianteering wonking edge brightness seemed very reasonable and plausible to me. I feel like this discussion may not be fully finished yet... at the very least I want to know how much it costs to mail $5 across the world

 

[blueMA]

Since I don’t believe I own any stockings - but am rather fond of my few hats - it was a conveniently mixed metaphor An explanation of over-obstruction wonking pav reflection and brillianteering wonking edge brightness seemed very reasonable and plausible to me. I feel like this discussion may not be fully finished yet... at the very least I want to know how much it costs to mail $5 across the world

I kept looking at your kitty's hat that looks like a Christmas stocking and hoped it was small and edible
These days $5 transfer is done on a cell phone.

This was awesome. Despite the new proportions, I think we still learned why a diamond can look distorted, thanks to the experts.

 

[gm89uk]

Kudos to the sceptics!

 

[yssie]

@Rockdiamond @Wink @John Pollard @Garry H (Cut Nut) @Karl_K @david b

Re-reading some posts... we know that cut grade will be demoted if a stone exhibits what the GIA considers excessive brillianteering (and know that the GIA has little tolerance for it but that’s a different topic) - Cut grade affected by brillianteering...

1. If a stone has both proportions-based reasons to demote cut grade and “excessive brillianteering” (that would have been sufficient to drop cut grade without other proportions considerations) will Cut grade affected by brillianteering be noted on the report?

2A. Can “excessive brillianteering” cause cut grade demotion from all cut grades? Ie. Cut grade affected by brillianteering can be the cause of demotion from EX to VG. Can it cause demotion from VG to Good?

2B. Can “excessive brillianteering” cause a single-grade demotion only? (Ie. Wouldn’t ever be reason to drop cut grade from EX to Good).

I don’t want to deal with calling GIA and google isn’t answering

 

[Diamond_Hawk]

This thread is the most fun I’ve seen on PS in some time. Bravo to all posters, with a nod to the almost-melee between John and Garry, my favorite line so far:

People and "consistency of subjective critique"... scaled over time or geography... don't go hand in hand

 

[Lorelei]

This thread is the most fun I’ve seen on PS in some time. Bravo to all posters, with a nod to the almost-melee between John and Garry, my favorite line so far:

I agree and Yssie's a genius, as us Brits say, end of!

 

[John P]

Such is the life of a public defender.

It is 100% sure the cert for the picture

...

One thing is sure here the diamond picture is of the diamond certificate shown.

...

A big apology from every one!!!
I pasted the wrong J SI2 Good cut 2.07 Certificate that was on my desktop.

Thank you @david b for returning here and changing your plea. The truth was always the goal.

@flyingpig , @Rockdiamond , @yssie (here, take my hat, I'll stand in the rain)... You may not know it, but I initially set out using the DC assessment to support your comments. But when the frame fit as it did - and I spent a long time pondering lighting effects I've seen coupled with tilt and half-facet wonk - I decided I had to give the benefit of the doubt to a fellow professional taking time to post here. I'm hoping you don't hold it against me too much.

@Garry H - Fair play, mate. It's my shout in Vegas in a couple of weeks.

If a stone has both proportions-based reasons to demote cut grade and “excessive brillianteering” (that would have been sufficient to drop cut grade without other proportions considerations) will Cut grade affected by brillianteering be noted on the report?

I've received two different answers to that question, albeit they are 10 years apart... But you're barking up one of the trees I climbed. I'm guessing you knew that.

 

[Karl_K]

The teacher can still make the students even as Knights eat humble pie.
For those that don't know Garry has been my teacher for almost 15 years now and Sir Johns for even longer.
Well played Sir Garry.

 

[yssie]

I've received two different answers to that question, albeit they are 10 years apart... But you're barking up one of the trees I climbed. I'm guessing you knew that.

I did not... I thought they were quite straightforward questions... esoteric, possibly, but straightforward...

...

 

[John P]

Actual data: 2.01 carat, 7.88 - 7.94 x 5.00 mm, 61T, 63.2D, 40.0 CA, PA 40.2, 55-80, nc.

During our second round in Vegas I'd like to explore how both our DC models could be so off. As a nod to the software, I've done analysis using photos dozens of times for re-cut consultation (though not as tilted). When receiving the actual diamonds it always turned out to be reliable. Not so much here.

 

[Karl_K]

On the topic of si3.
Gia needs to tighten up their grading and better sync their different labs before worrying about adding another grade.
The si2/i1 split has always been a problematic one.
The best i1s were and are often much better than the worst si2s.
I don't see how adding another grade would help that any.

 

[david b]

every grade of clarity and color is a range D----------E-------F---------G, same is the clarity -----SI1--------------SI2---------(?SI3)----------I1
If part of the SI2s are eye clean and part are not there is a visual difference between this SI2 or another SI2, the ones that are not eye clean should be SI3.
So at least if i offer a customer an SI2 I will not need to check if it is eyeclean

 

[blueMA]

every grade of clarity and color is a range D----------E-------F---------G, same is the clarity -----SI1--------------SI2---------(?SI3)----------I1
If part of the SI2s are eye clean and part are not there is a visual difference between this SI2 or another SI2, the ones that are not eye clean should be SI3.
So at least if i offer a customer an SI2 I will not need to check if it is eyeclean

Well... nowadays you have to verify even SI1 and VS2 whether it's eye-clean rather frequently. I know SI1s are supposed to be eye-clean, but even over a decade ago I saw many SI1s that were not eye-clean. What's actually needed is for the GIA tighten up their grading criteria.

 

[Garry H (Cut Nut)]

every grade of clarity and color is a range D----------E-------F---------G, same is the clarity -----SI1--------------SI2---------(?SI3)----------I1
If part of the SI2s are eye clean and part are not there is a visual difference between this SI2 or another SI2, the ones that are not eye clean should be SI3.
So at least if i offer a customer an SI2 I will not need to check if it is eyeclean

DAVID YOU ARE SO VERY WELCOME HERE. Many trade folk have come and made statements, been torn apart by the community and run away. I think the questioning we get from these many very smart participants addicted to diamonds keeps me and us growing in knowledge.

 

[Garry H (Cut Nut)]

Actual data: 2.01 carat, 7.88 - 7.94 x 5.00 mm, 61T, 63.2D, 40.0 CA, PA 40.2, 55-80, nc.

During our second round in Vegas I'd like to explore how both our DC models could be so off. As a nod to the software, I've done analysis using photos dozens of times for re-cut consultation (though not as tilted). When receiving the actual diamonds it always turned out to be reliable. Not so much here.

Hi John, my assessment was focusing on the pavilion reflection (which is only slightly affected by crown angle) because that was the easiest way to ID it was not the stone / cert.
I was off by 0.25degrees. So not that bad in my view.
You need to addd in the additional draft reflections.

And yes, a round is great, but I want the $5 so I can frame it