Why does this diamond image have so much darkness around the arrows?

[DiaDan]

Is this just obstruction with the camera equipment?

 

[newtojewels]

To me this looks like "paddling" which is a particular kind of obstruction/reduced light return. Here's a thread with a brief discussion and then links to a more in-depth discussion on obstruction: https://www.pricescope.com/community/threads/paddle-arrows-obstruction.145522/

 

[Dreamer_D]

To me this looks like "paddling" which is a particular kind of obstruction/reduced light return. Here's a thread with a brief discussion and then links to a more in-depth discussion on obstruction: https://www.pricescope.com/community/threads/paddle-arrows-obstruction.145522/

This is correct.

This diamond will look a darker around the ends of the arrows than another, better cut diamond will look.

 

[Karl_K]

Whats the numbers from the report or the report #?
It could be just fine in person.
The video setups apply more obstruction than a person looking at them would.

 

[DiaDan]

Whats the numbers from the report or the report #?
It could be just fine in person.
The video setups apply more obstruction than a person looking at them would.

The report number is 2507461262 (GIA)

 

[Karl_K]

2507461262

Fine at normal viewing conditions.
Paddles a bit around 6 inches.

 

[AdaBeta27]

Fine at normal viewing conditions.
Paddles a bit around 6 inches.

It's so cool that you can draw that conclusion. Do you run the numbers through a simulator, or just know from experience? Just curious. I admire your skills.

 

[Karl_K]

It's so cool that you can draw that conclusion. Do you run the numbers through a simulator, or just know from experience? Just curious. I admire your skills.

Its something I studied when designing the new igi round cut grade system.

 

[DiaDan]

Fine at normal viewing conditions.
Paddles a bit around 6 inches.

Thank you! Btw, what causes this paddling?

 

[Karl_K]

Thank you! Btw, what causes this paddling?

Where the diamond is drawing light from.
In that particular combo at very close distances it may be drawing light from your head in those areas. At normal viewing distance not an issue.
In the image its drawing light from the camera lens which provides more light blockage than you would at normal viewing distances.
The angles you block light from the diamond vary by distance.
To demo this look into a small compact mirror at close range your face fills the entire mirror but at full arms length it does not.

 

[DiaDan]

Where the diamond is drawing light from.
In that particular combo at very close distances it may be drawing light from your head in those areas. At normal viewing distance not an issue.
In the image its drawing light from the camera lens which provides more light blockage than you would at normal viewing distances.
The angles you block light from the diamond vary by distance.
To demo this look into a small compact mirror at close range your face fills the entire mirror but at full arms length it does not.

Makes sense. Can you share specifically which spec combo of the diamond would usually show this behavior?

 

[Karl_K]

Makes sense. Can you share specifically which spec combo of the diamond would usually show this behavior?

upper girdle facet angles relative to lower girdle facet angles which are not on the reports but can be inferred from the other angles to some degree.

 

[Karl_K]

upper girdle facet angles relative to lower girdle facet angles which are not on the reports but can be inferred from the other angles to some degree.

That should have been crown angle and upper girdle facet angles relative....

 

[Garry H (Cut Nut)]

Here is a little girl to show you how it happens:

 

[DiaDan]

Here is a little girl to show you how it happens:

This is an interesting illustration! I assume the camera equipment is set up the same way for all these diamond image captures for a particular gemologist. So the characteristics of the diamond have a huge part in it when everything else is held constant. This is where Karl_K's explanation comes in.

 

[DiaDan]

That should have been crown angle and upper girdle facet angles relative....

Got it, very interesting!