Lower girdle facet numbers?

[bright ice]

Give me your thoughts regarding how much of a difference in lower girdle facets you would be ok with if your were trying to match a pair of stones for earrings. We will use as an example a 1.7ish ct each stone because I know the size will be more notable on larger stones.

I ask because my biggest concern is the diameter matching well but I don't want to have too drastic of a difference in the LGFs.

I know this is a matter of personal taste.

 

[heididdl]

Huh select stone by mm why would lower girdle affect table size. Are you buying round stones? I have nevver heard anyone worry about the lower girdle. Just buy stones that have similar size. color and clarity......

 

[bright ice]

Because of the arrow size difference, fatter = broader, slimmer = skinner.

 

[diamondseeker2006]

It's possible that you and I are the only people on earth who have ever looked at that as a factor for choosing matching studs!

 

[John P]

Give me your thoughts regarding how much of a difference in lower girdle facets you would be ok with if your were trying to match a pair of stones for earrings. We will use as an example a 1.7ish ct each stone because I know the size will be more notable on larger stones.

This is dependent on make. 60-60 makes typically have a higher lower-half average than Tolk-Ideal makes, which have a higher average than antique/transitional cuts.

If you're talking about Tolk-Ideals, most specialized productions keep lower half averages between 75-80%. Anything inside those numbers will be complimentary, diamond to diamond, as long as the other parameters are within nominal tolerances and the cut-quality is consistent. If you want to get really picky, so you confuse one stud with the other, keep the lower half averages within 2 from each other. Be aware that GIA Reports round the lower half numbers to the nearest 5%, so they're not useful for the level of detail you're seeking. In such cases, photos like standardized Mag, IS, ASET can be useful for some interpretation beyond the report numbers.

Here's a past thread with some discussion and graphics.
https://www.pricescope.com/communit...rdle-length-affect-face-up-performance.87181/

It's possible that you and I are the only people on earth who have ever looked at that as a factor for choosing matching studs!

I love this, yet au contraire, mon diamondseeker ...In the fullness of time I've had myriad queries along these very lines, for studs as well as making a personal center-stone selection. Of course I'm an acknowledged cut-nerd, working with colleagues and friends who also obsess on (arguable) minutia like this. Either way, I love the question and would say you're both in good company.

 

[bright ice]

Give me your thoughts regarding how much of a difference in lower girdle facets you would be ok with if your were trying to match a pair of stones for earrings. We will use as an example a 1.7ish ct each stone because I know the size will be more notable on larger stones.

This is dependent on make. 60-60 makes typically have a higher lower-half average than Tolk-Ideal makes, which have a higher average than antique/transitional cuts.

If you're talking about Tolk-Ideals, most specialized productions keep lower half averages between 75-80%. Anything inside those numbers will be complimentary, diamond to diamond, as long as the other parameters are within nominal tolerances and the cut-quality is consistent. If you want to get really picky, so you confuse one stud with the other, keep the lower half averages within 2 from each other. Be aware that GIA Reports round the lower half numbers to the nearest 5%, so they're not useful for the level of detail you're seeking. In such cases, photos like standardized Mag, IS, ASET can be useful for some interpretation beyond the report numbers.

Here's a past thread with some discussion and graphics.
https://www.pricescope.com/communit...rdle-length-affect-face-up-performance.87181/

It's possible that you and I are the only people on earth who have ever looked at that as a factor for choosing matching studs!

I love this, yet au contraire, mon diamondseeker ...In the fullness of time I've had myriad queries along these very lines, for studs as well as making a personal center-stone selection. Of course I'm an acknowledged cut-nerd, working with colleagues and friends who also obsess on (arguable) minutia like this. Either way, I love the question and would say you're both in good company.

Thanks John, I guess my OCD is playing in here. I obviously nit-pick most things but when you are talking about buying a super-ideal diamond that cost big bucks, every little nuance can make a difference is cost

 

[John P]

Thanks John, I guess my OCD is playing in here. I obviously nit-pick most things but when you are talking about buying a super-ideal diamond that cost big bucks, every little nuance can make a difference is cost

I respect the OCD. It's me, too.

With that said, do what you wish. However I can also frame this another way: Let's say you find a perfect pair of top-shelf diamonds with matching criteria, except one has a 75-76% lower half average and the other has 79-80%. Hey, if they're both stunners you could use them to light up any room on your ears *and* to enjoy (even show your OCD friends) the cool but subtle-character-differences that exist among quality performers.

 

[diamondseeker2006]

YAY!!! There are three of us!!! Thanks, John!!

My superideal studs (1.16 ct each) have 76 and 78. I really can't tell them apart without magnification. But my goal is to not be able to tell them apart. That is why I personally wouldn't be able to do 75-76 with an 80.

 

[bright ice]

Give me your opinion on how these 2 will pair up please.

#1 #2
Diameter
7.72 x 7.75 x 4.66 7.70 x 7.73 x 4.76
Table
58 57.5
Depth
60.3 61.7
Crown Angle
34.0 34.4
Pavilion Angle
40.6 40
LGF
80 77
Star
49.70 48.0
Crown%
14.2 14.6

I think I got all of the measurements right.

 

[diamondseeker2006]

I know you are wanting John to comment on those numbers and I hope he will see it. But I want to be sure you know that I think those are a fine choice. I do not think the lgf difference will be noticeable. Tables and diameter are great and those are the two most important factors to match aside from color. These are going to give you a really nice diameter and I think if you want to do this just once, going for the larger size will be worth it. Then I will have to deal with DSS when I see them!!!

 

[bright ice]

I know you are wanting John to comment on those numbers and I hope he will see it. But I want to be sure you know that I think those are a fine choice. I do not think the lgf difference will be noticeable. Tables and diameter are great and those are the two most important factors to match aside from color. These are going to give you a really nice diameter and I think if you want to do this just once, going for the larger size will be worth it. Then I will have to deal with DSS when I see them!!!

Thanks DS, I appreciate your opinion almost as much as John's I want to try keeping DSS at bay