HCA 59% table and 40.4 pavilion angle

[steppapajon]

I was playing around with the HCA tonight after I read about the 5:1 crown/pavilion angle ratio. I used 59% table and 61% depth.
I was surprised that crowns from 32-36.5 fell below the 2 mark using the same 40.4 pavilion angle. Even more surprising is that all of the combinations fall in the GIA very good cut range except 32 and 32.5 and they are GIA good cuts.
32 61% depth, 59% table, 32° crown angle, 40.4° pavilion angle HCA 1.9
32.5 61% depth, 59% table, 32.5° crown angle, 40.4° pavilion angle HCA 1.8
33 61% depth, 59% table, 33° crown angle, 40.4° pavilion angle HCA 1.6
33.5 61% depth, 59% table, 33.5° crown angle, 40.4° pavilion angle HCA 1.4
34 61% depth, 59% table, 34° crown angle, 40.4° pavilion angle HCA 1.2
34.5 61% depth, 59% table, 34.5° crown angle, 40.4° pavilion angle HCA 1.1
35 61% depth, 59% table, 35° crown angle, 40.4° pavilion angle HCA 1.1
35.5 61% depth, 59% table, 35.5° crown angle, 40.4° pavilion angle HCA 1.2
36 61% depth, 59% table, 36° crown angle, 40.4° pavilion angle HCA 1.3
36.5 61% depth, 59% table, 36.5° crown angle, 40.4° pavilion angle HCA 1.9
I am wondering if anyone hase IS or ASET images of the combinations on either end of this list.
The 32 and 32.5 look like the may be a place to find bargain price on a decent stone if they check out.
Hope someone finds this useful.
SPJ

 

[teobdl]

Good info in the archives that touches on this

[URL='https://www.pricescope.com/community/threads/why-did-i-pick-a-gia-vg-cut-over-a-gia-exc-cut-am-i-nuts.67659/']https://www.pricescope.com/community/threads/why-did-i-pick-a-gia-vg-cut-over-a-gia-exc-cut-am-i-nuts.67659/[/URL]

 

[yssie]

I was playing around with the HCA tonight after I read about the 5:1 crown/pavilion angle ratio. I used 59% table and 61% depth.
I was surprised that crowns from 32-36.5 fell below the 2 mark using the same 40.4 pavilion angle. Even more surprising is that all of the combinations fall in the GIA very good cut range except 32 and 32.5 and they are GIA good cuts.
32 61% depth, 59% table, 32° crown angle, 40.4° pavilion angle HCA 1.9
32.5 61% depth, 59% table, 32.5° crown angle, 40.4° pavilion angle HCA 1.8
33 61% depth, 59% table, 33° crown angle, 40.4° pavilion angle HCA 1.6
33.5 61% depth, 59% table, 33.5° crown angle, 40.4° pavilion angle HCA 1.4
34 61% depth, 59% table, 34° crown angle, 40.4° pavilion angle HCA 1.2
34.5 61% depth, 59% table, 34.5° crown angle, 40.4° pavilion angle HCA 1.1
35 61% depth, 59% table, 35° crown angle, 40.4° pavilion angle HCA 1.1
35.5 61% depth, 59% table, 35.5° crown angle, 40.4° pavilion angle HCA 1.2
36 61% depth, 59% table, 36° crown angle, 40.4° pavilion angle HCA 1.3
36.5 61% depth, 59% table, 36.5° crown angle, 40.4° pavilion angle HCA 1.9
I am wondering if anyone hase IS or ASET images of the combinations on either end of this list.
The 32 and 32.5 look like the may be a place to find bargain price on a decent stone if they check out.
Hope someone finds this useful.
SPJ

32/32.5 w/ 60table - perhaps great for earrings! But no good for anything wherein someone might lean over it to admire it and thereby block incident light, like in a ring - it'd have exaggerated over-obstruction issues (too many facets angled such that they return what's right in front of them, which in those scenarios is the dark side of your head )

36.5/37+ & 40.4 can be lovely with smaller table, depending on other proportions!

ETA: video on head-obstruction by Garry Holloway: http://www.screencast.com/users/Pricescope/folders/Default/media/64f27d25-9e00-4e29-96e3-e43ebed12a60
You'll need an extension to view it if you use chrome, it takes you to the download page and gives you instructions.