What are those numbers from the AGS cert?

[zeiss]

Hi all,

What are those numbers circled in red in the diamond plot? How do they affect the light performance or characteristic of the diamond? And what are the ideal values for those, if any?

Thanks!

Zeiss

 

[zeiss]

image attached.

 

[Ellen]

The one on top is the star measurement, and the one on bottom is the lower girdle facet measurement.

Here''s just one of many threads on here about these. If you want more info, just do a search. HTH!

https://www.pricescope.com/community/threads/lgf-and-stars.36793/

 

[zeiss]

Ellen, thanks for the link!

Does it means that given 2 stones with the same ideal crown/pavillion angles, a stone with longer lower girdle facet will be more sparky?

Zeiss

 

[Lorelei]

Date: 1/9/2009 12:03:21 PM
Author: zeiss
Ellen, thanks for the link!

Does it means that given 2 stones with the same ideal crown/pavillion angles, a stone with longer lower girdle facet will be more sparky?

Zeiss

The crown and pavilion angles have the greatest impact on light performance/ sparkle, - this article from GOG goes into detail concerning the LFG's and their importance.

http://www.goodoldgold.com/Articles/MinorFacets/

This is also a good thread which may be useful to you - https://www.pricescope.com/community/threads/how-does-lower-girdle-length-affect-face-up-performance.87181/

 

[Ellen]

Date: 1/9/2009 12:03:21 PM
Author: zeiss
Ellen, thanks for the link!

Does it means that given 2 stones with the same ideal crown/pavillion angles, a stone with longer lower girdle facet will be more sparky?

Zeiss

Along with Lorelei''s links, there''s a video on this page that may help. I can''t copy it seperately, so way down the page (about 3/4) is a video that says,

A very interesting comparison of a 3ct GIA Ex with 40.8 pav/35.0 crown alongside a 2.68ct GIA Ex w/40.8 pavilion/34.5 and a 3ct Eighternity. The two 57 facet rounds differ most in their lower girdle facet length. One at 75% and the other at 82.6%. The difference in appearance is notable.


Watch that and see if it helps.

http://goodoldgold.com/Diamond_Videos/

 

[zeiss]

Thanks for the links.

Is there an ''ideal range'' for the lower girdle length?

Thanks!

 

[Ellen]

Date: 1/9/2009 1:02:22 PM
Author: zeiss
Thanks for the links.

Is there an ''ideal range'' for the lower girdle length?

Thanks!

Most very well cut stones tend to fall in the range of 75-80. However, don''t get too hung up on them. The cutter of the stone cuts what''s appropriate for a particular stone. Just concentrate on the overall cut of the stone, that''s most important.

 

[Lorelei]

Date: 1/9/2009 1:07:28 PM
Author: Ellen

Date: 1/9/2009 1:02:22 PM
Author: zeiss
Thanks for the links.

Is there an ''ideal range'' for the lower girdle length?

Thanks!

Most very well cut stones tend to fall in the range of 75-80. However, don''t get too hung up on them. The cutter of the stone cuts what''s appropriate for a particular stone. Just concentrate on the overall cut of the stone, that''s most important.

Ditto Miss Ellen!

 

[zeiss]

Correct me if I''m wrong. By watching the GOG video that Ms Ellen posted earlier, it seems to me that the stone with longer LGF length is a clear winner over the one with 75% LGF length?

Thanks!

 

[Ellen]

Date: 1/9/2009 3:54:31 PM
Author: zeiss
Correct me if I'm wrong. By watching the GOG video that Ms Ellen posted earlier, it seems to me that the stone with longer LGF length is a clear winner over the one with 75% LGF length?

Thanks!

To you maybe.

That's the thing, there is no "right or wrong" look to a diamond, it's all personal! It's what makes you go OOOH.

If that seems to be stones with longer lgf's, then that's the type for you!


And you're welcome!