What is the ideal girdle?

[Gwendalyn]

In a round diamond, thin to medium or medium the ideal girdle?

Thank You,

Gwendalyn

 

[crombopulent]

I think a medium girdle is ideal. Girdles that are too thin risk damage to the stone. The drawback of thick girdles is that they can "hide" carat weight that won't translate into the face-up size.

 

[headlight]

Something I’ve noticed is that the AGS000 stones seem to have more of thin-to-medium girdles, whereas GIAXXX stones seem to have more of medium-to-slightly thick girdles.

 

[Kaycee2018]

My e-ring diamond is GIA graded with a thin to medium girdle, which I understand (but I’m no expert) is most desirable in order to maximize spread without compromising integrity. But of all the things to compromise on when choosing a MRB diamond, going with a medium to slightly thick girdle is a non-issue. Just avoid very Or extremely thin and very or extremely thick.

 

[John P]

Girdle thickness is not a constant, every descriptor involves a sliding scale.

These posts, from some handsome young chap may provide insight.

girdles?!

I have been looking at RB ideal cut diamonds, and have noticed that the girdle size can differ between ideals. Which is better for a 6 prong solitare setting. I have noticed that a few of you have mentioned something about thin girdles being prone to chipping. Thanks again, the feedback has...

www.pricescope.com

 

[Garry H (Cut Nut)]

The answer is it depends on the size of the diamond.

Once upon a time GIA were clever. They graded girdle thickness by what it meant.
It seems now they have gotten lazy and use % measures from a scanner.
This 10ct diamond has a half a millimetre thick girdle - that would have been classed as Thick 15 years ago.

While this medium girdle is only 0.15mm (paper thin and at risk of chipping). Previously GIA would have grade this as thin or Very Thin.

 

[AV_]

@Garry H (Cut Nut) What was the good old standard? (or, what is a good standard)

 

[Texas Leaguer]

In a sense there is no ideal girdle thickness, just as there is not an ideal table size or crown angle. There are instead narrow ranges.

With girdle thickness the assessment is essentially punitive. You don't get credit for having an awesome girdle. You can only get penalized if the girdle is too thin ( prone to chipping) or too thick (hiding weight).

One might be tempted to make the argument that a medium girdle (with no variation) is ideal, but that's a bit like arguing that the ideal table size is 56 because it is right between 53 and 58.

 

[Dancing Fire]

Thin to med is fine...

 

[kenny]

DF, you beat me to it. ............ birds of a feather, as they say.

I was going to post that this one looks pretty ideal.

 

[Garry H (Cut Nut)]

In a sense there is no ideal girdle thickness, just as there is not an ideal table size or crown angle.
One might be tempted to make the argument that a medium girdle (with no variation) is ideal, but that's a bit like arguing that the ideal table size is 56 because it is right between 53 and 58.

My point earlier Bryan was girdle (and table sizes) should be related to the stone size.
They were when GIA graded using human judgement.
Now, like AGS, a 100ct diamond medium has too fat a girdle (and should have a very small table) and under half a carat should have a slightly thick girdle (the way they measure now) (and a larger table size since fire and scintillation is not happening much in smaller stones - its all about the brilliance).

 

[matt_k]

Something I’ve noticed is that the AGS000 stones seem to have more of thin-to-medium girdles, whereas GIAXXX stones seem to have more of medium-to-slightly thick girdles.

ive totally noticed that as well. and not only do the AGS thin-med girdle stones have better light performance, they also have better spread than a GIA thin-slightly thick(I have seen 0.62 carat AGS 000 thin-medium girdle RBCs face up slightly bigger than GIA XXX thin-slightly thick girdle 0.65 carat diamonds pretty often, in fact).

 

[Garry H (Cut Nut)]

ive totally noticed that as well. and not only do the AGS thin-med girdle stones have better light performance, they also have better spread than a GIA thin-slightly thick(I have seen 0.62 carat AGS 000 thin-medium girdle RBCs face up slightly bigger than GIA XXX thin-slightly thick girdle 0.65 carat diamonds pretty often, in fact).

That is not even allowing for the stones GIA gave XXX to that were 65% depth with cheated girdles!

 

[matt_k]

That is not even allowing for the stones GIA gave XXX to that were 65% depth with cheated girdles!

I gotta say that it is an honor to have @Garry H (Cut Nut) respond to one of my posts. I still LOVE his idealscope and asset scope that I bought a few years ago. Marvelous little inventions!

 

[Garry H (Cut Nut)]

I gotta say that it is an honor to have @Garry H (Cut Nut) respond to one of my posts. I still LOVE his idealscope and asset scope that I bought a few years ago. Marvelous little inventions!

Thanks very much Matt. I am on a mission to improve diamond cut quality.
Here is some info on what I was referring to

GIA tricked & cheated: +63% depth XXX diamonds

https://www.diamonds.net/Magazine/Article.aspx?ArticleID=64438&RDRIssueID=195 A cut grade of Excellent from the Gemological Institute of America (GIA) is a target many diamond manufacturers are eager to reach. Recently, some of them have gotten creative in their efforts to achieve that goal — a...

www.pricescope.com

 

[daisygrl]

Thanks very much Matt. I am on a mission to improve diamond cut quality.
Here is some info on what I was referring to

GIA tricked & cheated: +63% depth XXX diamonds

https://www.diamonds.net/Magazine/Article.aspx?ArticleID=64438&RDRIssueID=195 A cut grade of Excellent from the Gemological Institute of America (GIA) is a target many diamond manufacturers are eager to reach. Recently, some of them have gotten creative in their efforts to achieve that goal — a...

www.pricescope.com

@Garry H (Cut Nut) Speaking of a cut... I have had this on my mind forever... it is believed (by many PS's) that chunkier crown in combination with a smaller table produce more fire. Suppose, we are talking about and only about super ideal cuts. Is it correct to believe that, let's say, 56.7 table and 34.3 crown (super ideal) will produce less fire than 55 table and 34.6 crown (super ideal)? Is that a rule? Does it go case by case? Why is it that a lot of people prefer smaller table and chunkier crown?

 

[headlight]

Hi @daisygrl ! I love the "profile" of the small table and higher crown. This is a question for @Garry H (Cut Nut) , but wouldn't the angles still need to work together, not merely just because it is a small table + higher crown??? Altho, with that said, I have a pair of old mine cushion cut studs... I don't know any measurements and, assuming they are not well-cut, their fire is fantastic. However, what I wanted to address was your comment regarding super ideals and these varying measurement "styles" and how they compare with regard to fire, super ideal vs super ideal: So my newly recut BGD AGS000 is spready... table of 57.4% and crown angle of 37..7% and it is just as, if not more, fiery than my GIA3X with 55% table + 35% crown angle. (On that note, I have compared until my eyes hurt, and I think the diff in fire is negligible, it is just that the "style" of the flashes are a bit different, I just can't explain... maybe one day I can attend the PS gathering and show PSers in person!). They are also of different sizes... 8.51mm with the 57.4% table compared to an 8.01 mm with a 55% table... so the larger stone, in this case being the super ideal, is going to provide a more powerful "show". But herein lies the superb technology of the precision cuts... you can have a spreadier stone and not sacrifice on fire.

 

[daisygrl]

Hi @daisygrl ! I love the "profile" of the small table and higher crown. This is a question for @Garry H (Cut Nut) , but wouldn't the angles still need to work together, not merely just because it is a small table + higher crown??? Altho, with that said, I have a pair of old mine cushion cut studs... I don't know any measurements and, assuming they are not well-cut, their fire is fantastic. However, what I wanted to address was your comment regarding super ideals and these varying measurement "styles" and how they compare with regard to fire, super ideal vs super ideal: So my newly recut BGD AGS000 is spready... table of 57.4% and crown angle of 37..7% and it is just as, if not more, fiery than my GIA3X with 55% table + 35% crown angle. (On that note, I have compared until my eyes hurt, and I think the diff in fire is negligible, it is just that the "style" of the flashes are a bit different, I just can't explain... maybe one day I can attend the PS gathering and show PSers in person!). They are also of different sizes... 8.51mm with the 57.4% table compared to an 8.01 mm with a 55% table... so the larger stone, in this case being the super ideal, is going to provide a more powerful "show". But herein lies the superb technology of the precision cuts... you can have a spreadier stone and not sacrifice on fire.

Hi there @headlight - I wonder if your two stones you compared here have anything to do with the fact that one is AGS000 (more precise when it comes to numbers and a cut) and the other GIA3x (where they, sometimes heavily, round up/down the numbers.) I am sure BGD would not recut you something that would not sparkle at least as much as GIA stones.

Before I joined PS I preferred 34.3 crown over 34.7 (for me, best is 34.5) and larger table for colors I and down to get a bit more brightness. Now, I am not sure, I think I like both higher/lower crown, smaller/larger table... as long as it is not too "flat" (aka 34.1 or lower.)

 

[headlight]

Hi there @headlight - I wonder if your two stones you compared here have anything to do with the fact that one is AGS000 (more precise when it comes to numbers and a cut) and the other GIA3x (where they, sometimes heavily, round up/down the numbers.) I am sure BGD would not recut you something that would not sparkle at least as much as GIA stones.

Before I joined PS I preferred 34.3 crown over 34.7 (for me, best is 34.5) and larger table for colors I and down to get a bit more brightness. Now, I am not sure, I think I like both higher/lower crown, smaller/larger table... as long as it is not too "flat" (aka 34.1 or lower.)

I agree that going for larger table on color I and down for more brightness. I don't prefer the lower crown height %ages, the more "flat top" stones, yet my BGD recut is (due to what he had to work with) and I've come to appreciate it! But my heard still skips a beat when I see a stone with small table and high crown!

 

[matt_k]

Thanks very much Matt. I am on a mission to improve diamond cut quality.
Here is some info on what I was referring to

GIA tricked & cheated: +63% depth XXX diamonds

https://www.diamonds.net/Magazine/Article.aspx?ArticleID=64438&RDRIssueID=195 A cut grade of Excellent from the Gemological Institute of America (GIA) is a target many diamond manufacturers are eager to reach. Recently, some of them have gotten creative in their efforts to achieve that goal — a...

www.pricescope.com

Thanks for the link, @Garry H (Cut Nut) . Fascinating!

 

[Garry H (Cut Nut)]

[QUOTE="daisygrl, post: 4719752, member: 113900"
Before I joined PS I preferred 34.3 crown over 34.7 (for me, best is 34.5) and larger table for colors I and down to get a bit more brightness. Now, I am not sure, I think I like both higher/lower crown, smaller/larger table... as long as it is not too "flat" (aka 34.1 or lower.)
[/QUOTE]
Sorry, I think you are dreaming Daisy. There is no way you can tell the difference between such minuscule crown angles. The pavilion angle variant counts for 5 times the crown angle variant.
Ihave been called out by many for telling people not to split hairs. But in the abscence of loads of other data - you can not make those kinds of calls.

 

[Garry H (Cut Nut)]

Steep crowns to work must be combined with ever so slightly shallower pavilions. e.g 36 with 40.5
In larger diamonds this works really well because you get more splitting of virtual facets and more small colorful flashes. Slightly smaller tables as stones get larger compunds that effect - fortunately the nature of rough means that more larger stones like this are a natural consequence of nature and yeild.

 

[daisygrl]

I agree that going for larger table on color I and down for more brightness. I don't prefer the lower crown height %ages, the more "flat top" stones, yet my BGD recut is (due to what he had to work with) and I've come to appreciate it! But my heard still skips a beat when I see a stone with small table and high crown!

[QUOTE="daisygrl, post: 4719752, member: 113900"
Before I joined PS I preferred 34.3 crown over 34.7 (for me, best is 34.5) and larger table for colors I and down to get a bit more brightness. Now, I am not sure, I think I like both higher/lower crown, smaller/larger table... as long as it is not too "flat" (aka 34.1 or lower.)

Sorry, I think you are dreaming Daisy. There is no way you can tell the difference between such minuscule crown angles. The pavilion angle variant counts for 5 times the crown angle variant.
Ihave been called out by many for telling people not to split hairs. But in the abscence of loads of other data - you can not make those kinds of calls.
[/QUOTE]

Lol. I guess that is why I was not "so sure" which crown I like better because I looked at many diamonds (from 34.3 to 34.7 crown) and saw no difference. I mean, none! Thus, I had no preference whatsoever (I just know I don't like them too high.) But reading all the PS's preferences (higher crown, smaller table) got me confused. Not confused about what I like, rather about how they can tell/see the difference because I had my eyes crossed by looking at some diamonds they posted and I could not see higher/lower crown difference they were talking about.

 

[Garry H (Cut Nut)]

Sorry, I think you are dreaming Daisy. There is no way you can tell the difference between such minuscule crown angles. The pavilion angle variant counts for 5 times the crown angle variant.
Ihave been called out by many for telling people not to split hairs. But in the abscence of loads of other data - you can not make those kinds of calls.

Lol. I guess that is why I was not "so sure" which crown I like better because I looked at many diamonds (from 34.3 to 34.7 crown) and saw no difference. I mean, none! Thus, I had no preference whatsoever (I just know I don't like them too high.) But reading all the PS's preferences (higher crown, smaller table) got me confused. Not confused about what I like, rather about how they can tell/see the difference because I had my eyes crossed by looking at some diamonds they posted and I could not see higher/lower crown difference they were talking about.
[/QUOTE]
Mostly you will find people like 35.5 or 34 or 33ish but for different reasons and different purposes - e.g earrings pendants vs rings and braclets.
But whatever the crown angle it must be hooked up with an inverse pavilion angle:
35.5 40.5-6 or 34 40.8 41 or 33ish 41ish