IS image questions - yaw?

[Lula]

Hi, I have been considering this diamond:
crown 34.5
pav angle 41.0
depth 61
table 56.7
girdle thin-med
star 55
lower girdle 80

I have a few more days left to decide if I want to keep it. In person it is a bright, beautiful stone with wonderful brilliance and scintillation and small (but frequent) fire.

There''s something about the IS image that bugs me, though - what is all the black surrounding the arrow shafts? Is this head obstruction? Yaw? Evidence of poor symmetry? This is not a branded hearts and arrows stone, but it is being sold as a stone with hearts and arrows symmetry and it is AGS000

Thanks!

 

[strmrdr]

Has one small heart maybe 2. (large triangles near arrow shafts)
The rest of them are normal for that combo.

More near h&a than h&a but should be an excellent performer.

 

[Lorelei]

Date: 5/24/2009 2:41:10 PM
Author: strmrdr
Has one small heart maybe 2. (large triangles near arrow shafts)
The rest of them are normal for that combo.

More near h&a than h&a but should be an excellent performer.

Ditto

 

[John P]

Date: 5/24/2009 2:35:27 PM
Author:sarap333

There''s something about the IS image that bugs me, though - what is all the black surrounding the arrow shafts? Is this head obstruction? Yaw? Evidence of poor symmetry? This is not a branded hearts and arrows stone, but it is being sold as a stone with hearts and arrows symmetry and it is AGS000

Thanks!

What you are seeing is table reflection. This is, literally, the reflection of the table seen in the pavilion of the diamond in some lighting conditions. Diamond cutters have used this phenomenon since before scanners existed to judge pavilion depth.

The graphic below shows how table reflection increases as table size or pavilion depth increase. This diamond has a 43.5% pavilion depth (41 degree pavilion angle) so it lands between the bottom examples on the graphic, as seen in the Ideal-Scope image you posted. Bear in mind that such things are exaggerated in magnified still photos; table reflection it is not nearly as notable in normal viewing, especially when the diamond is in motion.

 

[Lula]

Hi, Thanks, Storm, for the explanation about the hearts (I can clearly see what you''re referring to). The diamond is a great performer, which is why I''m reluctant to let it go without some more thought. This forum has turned me into a geek -- which is why I''m on this blog on a holiday instead of grilling burgers with my family, who all think I''m nuts

John, your explanation and diagrams about table reflection were very helpful.I know that that is what I''m seeing when I look at the diamond from the top down, in certain lights, without moving the diamond. I''m just not sure I can live with the faint shadow of the table reflection.

But what I''m wondering is why this second diamond, which is very similar to mine in size and cut parameters, does not show the same black areas around the center (IS attached). Is it just because the table is smaller? Thanks for your help.


AGS000
Depth: 61.7%
Table: 55.5%
Girdle: Thin to slightly thick
Culet: None
Crown Angle: 34.1°
pavilion Angle: 41.0°
pavilion %: 43.20
Star 54
Lower girdle 77

 

[strmrdr]

lower girdle % + table size + shallower crown explain the difference.

 

[John P]

Date: 5/25/2009 9:04:27 AM
Author: sarap333

...Is it just because the table is smaller?...

Date: 5/25/2009 1:55:41 PM
Author: strmrdr
lower girdle % + table size + shallower crown explain the difference.

Yes and yes.

Do keep in mind how large these diamonds actually are (aren''t) IRL. Look at the size on your monitor and then consider actual mm size. We do live in a magnified world here on PS

 

[Lorelei]

Date: 5/25/2009 2:26:52 PM
Author: John Pollard

Date: 5/25/2009 9:04:27 AM
Author: sarap333

...Is it just because the table is smaller?...

Date: 5/25/2009 1:55:41 PM
Author: strmrdr
lower girdle % + table size + shallower crown explain the difference.

Yes and yes.

Do keep in mind how large these diamonds actually are (aren''t) IRL. Look at the size on your monitor and then consider actual mm size. We do live in a magnified world here on PS

A good reminder.