What is the best crown & pavillion angle?

[Samara83]

I read a note on here to pay special attention to the crown and pavilion angles of a diamond. What is considered to the best and/or very good?

 

[stone-cold11]

Play with the cut adviser.

https://www.pricescope.com/cutadviser.asp

Generally, stay below score of 2, within GIA Ex/ AGS Ideal is a save choice. Then request for an idealscope image.

 

[HVVS]

Date: 4/10/2010 9:44:06 PM
Author:Samara83
I read a note on here to pay special attention to the crown and pavilion angles of a diamond. What is considered to the best and/or very good?

depth - 60 - 62%
table - 54- 57%
crown angle - 34- 35 degrees
pavilion angle - 40.6- 41 degrees
girdle - avoid extremes, look for thin to slightly thick, thin to medium etc
polish and symmetry - very good and above

note - with crown and pavilion angles at the shallower ends ( CA 34- PA 40.6) and steeper ( CA 35- PA 41) check to make sure these angles complement in that particular diamond - eyeballs, Idealscope, trusted vendor input - check as appropriate!

quoting an old post by John Pollard:

With that said, here's a "Cliff's Notes" for staying near Tolkowsky/ideal angles with GIA reports (their numbers are rounded): A crown angle of 34.0, 34.5 or 35.0 is usually safe with a 40.8 pavilion angle. If pavilion angle = 40.6 lean toward a 34.5-35.0 crown. If pavilion angle = 41 lean toward a 34.0-34.5 crown.

GIA "EX" in cut is great at its heart, but it ranges a bit wider than some people prefer, particularly in deep combinations (pavilion > 41 with crown > 35).

quoting an old post by Todd Gray:

A good recipe for a diamond that has more brightness and less fire would be to have a larger table, flatter crown and deeper pavilion. Something along the lines of:

Crown angle: 33.0
Pavilion angle: 41.0
Table: 59-60%
Depth: 58-61%

The benefit of the above proportions is that the stone should have a slightly larger diameter for it's weight, due to the 1-2% shallower depth than your average Tolkowsky cut.

But that angle combination sits on a cliff-edge; just a small increase in either crown or pavilion (or a rounding-off error) can dramatically downgrade the light performance. Definitely don't go for a stone that's exactly on a carat boundary, because you can bet that the cutter compromised the beaiuty to attain the weight. 1.02ct or more should be safer, since the cutter had a little extra weight to play with, to create a good stone.

 

[Lorelei]

Date: 4/10/2010 10:11:10 PM
Author: HVVS

Date: 4/10/2010 9:44:06 PM
Author:Samara83
I read a note on here to pay special attention to the crown and pavilion angles of a diamond. What is considered to the best and/or very good?

depth - 60 - 62%
table - 54- 57%
crown angle - 34- 35 degrees
pavilion angle - 40.6- 41 degrees
girdle - avoid extremes, look for thin to slightly thick, thin to medium etc
polish and symmetry - very good and above

note - with crown and pavilion angles at the shallower ends ( CA 34- PA 40.6) and steeper ( CA 35- PA 41) check to make sure these angles complement in that particular diamond - eyeballs, Idealscope, trusted vendor input - check as appropriate!

quoting an old post by John Pollard:

With that said, here's a 'Cliff's Notes' for staying near Tolkowsky/ideal angles with GIA reports (their numbers are rounded): A crown angle of 34.0, 34.5 or 35.0 is usually safe with a 40.8 pavilion angle. If pavilion angle = 40.6 lean toward a 34.5-35.0 crown. If pavilion angle = 41 lean toward a 34.0-34.5 crown.

GIA 'EX' in cut is great at its heart, but it ranges a bit wider than some people prefer, particularly in deep combinations (pavilion > 41 with crown > 35).

quoting an old post by Todd Gray:

A good recipe for a diamond that has more brightness and less fire would be to have a larger table, flatter crown and deeper pavilion. Something along the lines of:

Crown angle: 33.0
Pavilion angle: 41.0
Table: 59-60%
Depth: 58-61%

The benefit of the above proportions is that the stone should have a slightly larger diameter for it's weight, due to the 1-2% shallower depth than your average Tolkowsky cut.

But that angle combination sits on a cliff-edge; just a small increase in either crown or pavilion (or a rounding-off error) can dramatically downgrade the light performance. Definitely don't go for a stone that's exactly on a carat boundary, because you can bet that the cutter compromised the beaiuty to attain the weight. 1.02ct or more should be safer, since the cutter had a little extra weight to play with, to create a good stone.

Ditto HVVS, use the above as a guide and always confirm the numbers with an Idealscope image. Also you can go larger on table size if you prefer as long as the angles are within good range, I would suggest an upper limit of 61%. With the HCA it can sometimes give a good score to stones that have steep pavilion angles if the crown angle is correspondingly shallow, but steep pavilions can have undesirable issues in some cases such as leakage and colour entrapment so if you want to narrow the field and increase your chances of getting a well cut diamond, use the ranges given above and try to keep pavilion angles between 40.6 and 41 degrees, one has more flexibility with crown angles generally.

 

[Andelain]

Thanks Lorelei and HVVS. That helped me put together a lot of things I''ve been learning here. You folks are the best.

 

[Lorelei]

Date: 4/11/2010 8:51:58 AM
Author: Lone_Wolfe
Thanks Lorelei and HVVS. That helped me put together a lot of things I''ve been learning here. You folks are the best.

We are glad to help, if you have any more questions just shout! Thats great to hear that some posts are helping things click into place for you!

 

[Rockdiamond]

Date: 4/10/2010 9:44:06 PM
Author:Samara83
I read a note on here to pay special attention to the crown and pavilion angles of a diamond. What is considered to the best and/or very good?

There's a lot of "taste" involved.
I strongly recommend you get out to see some real diamonds, if at all possible, to see what YOU prefer.

My guidelines would be much wider- limit the search to GIA EX or VG cut graded stones.