Pavillion/Crown Angle relationship

[dfb]

Admittedly I am not real clear on the relationship between the two - I undestand at an elementary level that one being shallow can be somewhat offset by the other being steep enough - and I think I read that shallow pavillion figures can possibly make the HCA score look better than maybe it should be - but I could be totally off with that comment - and that too shallow can make the body of the stone appear more dark than otherwise

Anyway - here are the figures - both angles and % - could someone that knows more than I suggest what you might expect from this combo? The GIA cert notes the cut as EX

Crown Angle = 34.5
Crown % = 15%
Pavillion Angle = 40.6
Pavillion % = 42.5
Overall Depth of the stone = 61.2%
Table = 57%

 

[JulieN]

In steep combo stones, you will observe under Ideal Scope (which is lighted from the back) more areas of white. White is the light from the back. So you are seeing straight through the stone. This is bad because it may look dead.

In shallow combo stones, you will observe under ASET more blue. Blue represents the light coming from 75 to 105 degrees, and will be the dark areas due to obscuration.

Stone is fine by the numbers, have it called in for more details.

 

[dfb]

Thank you Julie - I appreciate you taking the time to respond

 

[JulieN]

you're welcome. and lucky. (: I have sparing with my words lately.

 

[RockDoc]

Date: 4/15/2007 4:36:02 PM
Author: JulieN
In steep combo stones, you will observe under Ideal Scope (which is lighted from the back) more areas of white. White is the light from the back. So you are seeing straight through the stone. This is bad because it may look dead.

In shallow combo stones, you will observe under ASET more blue. Blue represents the light coming from 75 to 105 degrees, and will be the dark areas due to obscuration.

Stone is fine by the numbers, have it called in for more details.

Julie, the blue in the ASET is from 75-90 degrees.

Rockdoc

 

[JulieN]

Same thing, don't you think? For a total of 30 degrees blue.

 

[Garry H (Cut Nut)]

Date: 4/15/2007 6:58:29 PM
Author: JulieN
Same thing, don''t you think? For a total of 30 degrees blue.

Exactly - better brush up on that arithmetic Roc!

more info about crown and pavilion relationships here

http://www.diamond-cut.com.au/03_inverse_relationship.htm

note the Gilbertson scope via DiamCalc - 5 years before the ASET