Poll: Which is the AGS Ideal?

[Rhino]

So we're helping a client and narrowing down those options on the market which fall in the zenith of the GIA XXX/AGS Ideal range for rarest optics and value. We did in fact find one that hit the mark but thought these examples might be interesting to learn from.

Just some preliminary info.

They are all GIA XXX. I have provided certain additional info here for you in way of the proportional information and GIA FacetWare results as well as ASET's for light performance assessment.

Assuming this is important to the client, which of these do you think fall in the zenith of both GIA XXX and AGS Ideal?

You only get 1 vote and the person you are serving is making a rather large investment so look at all the data carefully. If you have any questions feel free to ask. After enough votes I'll share the PGS data on each of them.

Kind regards,
Rhino

 

[VoxExMachina]

Could you post actual pics of the diamonds or would that make it too easy?

I could see 1 and 2 being AGS ideal but people here said that AGS ideal or GIA triple EX or even a good HCA score isn't enough. ASET and IS can show which are good performers but can also be misleading. Not sure if anyone would pick any of these stones though since they like super ideals.

 

[diamondseeker2006]

I rarely choose by numbers alone and always recommend that buyers not do so. I like to see the magnified image of the stone and the ASET Image. I have seen a few AGS Ideal cut stones that I would not want, so in that respect, it could be any of the three stones (and I just don't want to do the work to try and figure out the numbers). The ASET appears to show the best stone of the three, although I would prefer seeing all three magnified images of the stone, too.

I'd tell the buyer not to worry about which would fall in AGS Ideal cut range and simply buy the best performing stone! (Actually, you probably can access better than these three for him or her!)

 

[diaya]

Hi Rhino,

Thanks for the posting! This is like a detective work trying to solve a mystery. As a beginner, I don't yet have an eye for diamonds IRL, so I am basing my choice of diamond by a more objective method - numbers from sarin scans and aset images. Based on the available data, I casted my vote. Can't wait to hear what people in the trade would pick for their customers!

 

[Dancing Fire]

IMO, None of the above...

 

[Medical]

Based on the title, I'd have to assume only one falls into AGS ideal range- which I think may be skewing the poll a bit towards the single choice options. Either way, will be interesting to find out the answer. Cool poll!

 

[CrazyBirdLady]

IMO, None of the above...

Plus 1

 

[JEJ]

IMO, None of the above...

Plus 1

Well someone hasn't voted then because I was the first 'none of the above'

 

[diamondseeker2006]

I think none are superideal. But the ideal cut range is wider than that.

 

[Rhino]

Thank you all for your votes at this time. Some other pix requested by Vox.

Could you post actual pics of the diamonds or would that make it too easy?

I could see 1 and 2 being AGS ideal but people here said that AGS ideal or GIA triple EX or even a good HCA score isn't enough. ASET and IS can show which are good performers but can also be misleading. Not sure if anyone would pick any of these stones though since they like super ideals.

Sure Vox. Here are images of each of the diamonds.

Diamond 1.


Diamond 2.


Diamond 3.

 

[Rhino]

Hi Rhino,

Thanks for the posting! This is like a detective work trying to solve a mystery. As a beginner, I don't yet have an eye for diamonds IRL, so I am basing my choice of diamond by a more objective method - numbers from sarin scans and aset images. Based on the available data, I casted my vote. Can't wait to hear what people in the trade would pick for their customers!

Diaya ... I'll confess ... my middle name is "Danger" and I do like to think of myself as a gemological detective.

I think you'll be interested to see how the actual results pan out in relation to the votes.

 

[Rhino]

I think none are superideal. But the ideal cut range is wider than that.

Yep. And you are correct that none are "super Ideal" or would qualify for Ascendancy.

 

[diamondseeker2006]

I am hoping this is an illustration to show why not to choose an AGS Ideal cut on paper alone.

I also hope you are telling your customer to buy #1!

 

[ccuheartnurse]

Interesting post Jon. I have to admit, I voted before I saw the pictures but since all 3 really didn't wow me, I chose #2 for personal reasons. Had good numbers & the biggest spread. Would make a good pendant stone though.

#1 looks to be a nice stone.

Looking forward to the conclusion.
Judy

 

[OoohShiny]

Going from the ASETs and pics, I'm not keen on No.3 at all, looks really leaky, No.2 doesn't look very symmetrical and looks to have some dead spots, and No.1 looks to me to be the best choice.

Going from the numbers, No.2 and No.3 look to have quite long lower halves and lower crowns!

But... I am noob, not at all confident I could pick a stone 'in real life" that was good, and I don't have enough understanding of how the crown and pavilion measurements interact!


I'm going with No.1, although I think maybe No.2 is as well??

I can't work out if this is a trick question... Maybe they all are Ideal, to illustrate breadth of variety in the cut? Or maybe none of them are, just to leep us on our toes?!

 

[Laila619]

3 looks awful, and the numbers are not good. Too leaky.

I like number 2. 1 looks good too, but it's got a steeper crown/shallower pav combo, which not everyone likes.

 

[16ocean]

my guess for the AGS 000 would be #2 but I like how #1 looks in the real life photos #3 ASET looks different.

Question: Why does #3 ASET look different ?

I think this is when a video of a side by side comparison would be beneficial if one couldn't get out to your neck of the woods

 

[emmebee]

Haha I'm thinking #3 because it might be a trick question.. And the red in the middle could reflect more light, therefore possibly "tricking" the computer? I feel like I've seen similar AGS0 ones and was shocked.

 

[Mayk]

I picked #1 before the pictures... Sticking with it after...

 

[marcy]

I picked #1 before the pictures... Sticking with it after...

Me too.

 

[thecat]

#1 if I've to pick but none according to my preferred specs. So which is the best performing?

 

[Rhino]

Good afternoon PS fam. Hope everyone had a great weekend. Ok ... firstly thank you kindly for your participation in voting. Most votes were for diamond #1, diamond #2 came in 2nd and as figured #3 with virtually none.

The correct answer to this survey was the last answer. "None of the above". Yep... none of these options made AGS Ideal.

Now for the rundown.

Here are the PGS results on #1. For those figuring the diamond did get AGS Ideal light performance, THAT was correct and a KUDOS to those who voted as this seemed like a logical choice. This diamond however was disqualified from being AGS Ideal for weight ratio. Ie. Even though the total depth of the diamond is 61.9% (not deep), the steeper crown angles (36+) gave the diamond a smaller than typical spread for its weight causing it to take the hit. Interesting to note that this one with the 36.2/40.6 w 58 table combo did in fact produce ideal optics though.



Diamond #2 was the biggest surprise to me. These are classic Tolkowsky proportions. 34.5 crown angle, 40.7 pavilion angle, 58% table with a 60.6% depth. I didn't even check the HCA on it but I'm confident the score would be under a 2.0. The diamond didn't make AGS Ideal for its optics. It took the accumulative hits in both "brightness" and "contrast" which I'm figuring happened in the ASET 40 analysis due to it's shallower depth as well as slightly steep angles on some of the upper halves. What many don't realize is AGS PGS (Performance Grading Software) takes into account two positions of head/body obstruction. One a 30 degree angular spectrum of obstruction and one at 40 degrees which would increase the head/body shadow reflections. If anyone has any inquiring about head/body obstruction feel free to ask.



I had to throw diamond #3 in here for the no brainer part of this quiz. While it'd never be a diamond that would make either our Ascendancy or Platinum Select lines we have seen some AGS Ideals with leakage bordering on this. Truth is though that each of the diamonds in this study all got the same AGS 1 rating yet for all different reasons. This one, because of it's leakage took accumulative hits in all aspects of brightness, dispersion, leakage and contrast.



Once again a sincere thanks for your participation and if you like these little nuggets I'll make an extra effort to share here from time to time.

Kindest regards,
Jonathan

 

[pfunk]

Interesting results. Very cool thread Rhino! Would love to see some more of these!

I have one question about the weight ratio. At what point does AGS ding a diamond for weight ratio? Is there a formula used to determine what the spread should theoretically be, and if it is a certain percentage smaller than that number it gets a deduction? Do they use the largest diameter, average diameter, smallest diameter?

 

[WinkHPD]

Interesting results. Very cool thread Rhino! Would love to see some more of these!

I have one question about the weight ratio. At what point does AGS ding a diamond for weight ratio? Is there a formula used to determine what the spread should theoretically be, and if it is a certain percentage smaller than that number it gets a deduction? Do they use the largest diameter, average diameter, smallest diameter?

Obviously, this is not Rhino, but here is the pertinent information that you asked for, directly from the AGSL website under their educational section. There is a nice slide show presentation about advanced cut grading that can be found here: http://www.agslab.com/members/content/docs/Complete_Explanation_of_AGS_Cut_System.pdf

From the wording, I believe that this slide presentation was written about the time that AGSL was introducing their new Performance based grading system, rather than the older system that they had been using.

‘Spread’ is an industry term that refers to a diamond’s face up size
compared to its weight. You can also call this ‘weight ratio’ or ‘millimeter
footprint versus weight’.
The classic example is that a fine make 1.00 carat round brilliant cut
diamond should have a ‘spread’ of about 6.5 millimeters. Naturally, you
would want to purchase the largest millimeter stone that weighs the least
amount and still performs. Why pay for unwanted weight?
For a one-carat diamond, the current AGS Ideal 0 proportions allow a
millimeter ‘spread’ range of 6.30 to 6.57 mm.

Most people would not consider a 1.00 carat round brilliant cut diamond
with a ‘spread’ of 6.30 millimeters to be an Ideal.
Therefore, we are using a 5% ‘spread’ factor for the round brilliant in our
new grading system. We are normalizing to the Tolkowsky cut with a 2.7%
girdle thickness at the mains and 1% at the scallops. This Tolkowsky
model will weigh 1.00 carat at 6.47 millimeters in diameter.
A tight ‘spread’ tolerance is a beautiful thing because it self corrects a lot
of cutting faults.
Cutters know how to ‘swindle’ our existing proportion sets to maximize
weight at the expense of beauty. We hope that the ‘spread’ component
will go a long way in furthering the world diamond community’s and
consumer’s perception of fine make. It’s also reasonable in today’s world
of precision diamond cutting. Lastly, it’s easy to teach and understand.

Wink

 

[Dancing Fire]

Good afternoon PS fam. Hope everyone had a great weekend. Ok ... firstly thank you kindly for your participation in voting. Most votes were for diamond #1, diamond #2 came in 2nd and as figured #3 with virtually none.

The correct answer to this survey was the last answer. "None of the above". Yep... none of these options made AGS Ideal.

Kindest regards,
Jonathan

What did I win?... an Octavia?..

 

[Rhino]

Thank you for posting that Wink.

DF ... you get a star.

 

[pfunk]

I guess I am still not completely understanding the weight ratio thing so if someone could help me out a little. What it sounds like to me is that AGS uses a standard tolk proportioned model with a set girdle thickness to determine what the diameter of an ideal diamond SHOULD be based upon its carat weight. What I don't get is what they mean by a 5% spread factor. Does that mean that the actual diameter needs to simply be within 5% of the "ideal" diameter? If so, does that mean either 5% larger OR 5% smaller than predicted is ok, or does that mean 2.5% on either side of what is "ideal"? Maybe you can use stone #1 as example? What was its carat weight (sorry if you already mentioned it)?

What is the "ideal" size for a 1 carat (6.47 mm I think?), 1.5 carat, and 2 carat stone based on the AGS tolk model stone?

 

[yssie]

I guess I am still not completely understanding the weight ratio thing so if someone could help me out a little. What it sounds like to me is that AGS uses a standard tolk proportioned model with a set girdle thickness to determine what the diameter of an ideal diamond SHOULD be based upon its carat weight. What I don't get is what they mean by a 5% spread factor. Does that mean that the actual diameter needs to simply be within 5% of the "ideal" diameter? If so, does that mean either 5% larger OR 5% smaller than predicted is ok, or does that mean 2.5% on either side of what is "ideal"? Maybe you can use stone #1 as example? What was its carat weight (sorry if you already mentioned it)?

What is the "ideal" size for a 1 carat (6.47 mm I think?), 1.5 carat, and 2 carat stone based on the AGS tolk model stone?

https://www.pricescope.com/wiki/diamonds/ags-ideal-cut-diamond
Spread: For rounds the DiamCalc factor should must be within + or -5% about 6.35 to 6.6mm for a 1.00ct stone. Princess spread factors should not be worse than -25, or about 5.3mm square.

 

[Dancing Fire]

I prefer a 1ct b/t 6.40 - 6.45mm. That just me.

 

[pfunk]

I guess I am still not completely understanding the weight ratio thing so if someone could help me out a little. What it sounds like to me is that AGS uses a standard tolk proportioned model with a set girdle thickness to determine what the diameter of an ideal diamond SHOULD be based upon its carat weight. What I don't get is what they mean by a 5% spread factor. Does that mean that the actual diameter needs to simply be within 5% of the "ideal" diameter? If so, does that mean either 5% larger OR 5% smaller than predicted is ok, or does that mean 2.5% on either side of what is "ideal"? Maybe you can use stone #1 as example? What was its carat weight (sorry if you already mentioned it)?

What is the "ideal" size for a 1 carat (6.47 mm I think?), 1.5 carat, and 2 carat stone based on the AGS tolk model stone?

https://www.pricescope.com/wiki/diamonds/ags-ideal-cut-diamond
Spread: For rounds the DiamCalc factor should must be within + or -5% about 6.35 to 6.6mm for a 1.00ct stone. Princess spread factors should not be worse than -25, or about 5.3mm square.

The numbers aren't making sense to me. If the 1.00 carat tolk normalized stone has a diameter of 6.47 mm, 5% of that diameter would be 0.324 mm. That would leave the +/-5% range at 6.15 to 6.79 mm which is a much larger range than 6.35 to 6.6mm. That's what is confusing me.