Minutiae of pav angles...

[angeline]

Hi there,

These two stones are really similar, just the pav angles (and depth) vary. I''m just wondering if anyone has an opinion as to which is the more optimal pav angle for a 34.5 crown. Anyway here''s the info:

Stone 1:

Depth: 60.9
Table: 57
Crown: 34.5
Pav: 40.6

Stone 2:

Depth: 61.8
Table: 57
Crown: 34.5
Pav: 40.8

They''re both GIA certs. As an aside do GIA actually measure the crown and pav or calculate them?

Thanks for any input as usual!

a

 

[diamondseeker2006]

See what the HCA scores are. Also, what are the stone diameters?

 

[JulieN]

GIA takes an average, and then rounds to the nearest fifth.

 

[whatmeworry]

You can''t tell because:
1. Optimal means different things. Optimal for maximizing brightness, maximizing fire, balancing both?
2. Even if you picked one category, there is no universal agreement on what the optimal angle is.
3. GIA rounds up angles in 0.2 degree increments when they report them. So let''s suppose that everybody agreed that 40.75 degrees is the optimal angle just because that''s what Marcel Tolkowsky said. Because of the rounding, stone 1''s angle may be 40.69 and stone 2''s could be 40.89 in which case stone 1 is closer to the optimal. Or it could be the case that stone 1''s angle is 40.69 and stone 2''s is 40.71, then stone 2 is closer to the optimal. But it could also be the case that stone 1 and stone 2 are really the same stone but are reported as different because of instrumentation error and rounding.
4. instrumentation error (your fav topic

). I believe GIA does actally measure the diamonds and the error is +/-0.2 degrees.
5. Also with GIA rounding that 34.5 crown could be 34.3 or 34.7.

anyway I say you can''t tell but nevertheless I think both angles seem optimal per HCA.

 

[angeline]

Date: 6/23/2007 3:52:57 PM
Author: diamondseeker2006
See what the HCA scores are. Also, what are the stone diameters?

Stone 1:

diameter: 8.13-8.17 HCA: .8 (from memory can''t be bothered doing it again!)
girdle is medium to slightly thick

stone 2:

8.03, HCA 1.5 (ditto above!)
girdle is slightly thick to thick (not my fave girdle )

 

[angeline]

whatmeworry - thanks for the examples, they're really helpful. I guess I need to get a Sarin on them. Stone 2 has a Sarin, stone 1 I would have to get WF to get in. I think I will do that then post the relevant numbers again more accurately.

LOL about the instrumentation error!

ETA: love your doggies!