How does a diamond reach the elusive excellent in spread?

[soontomarry2]

During the past few weeks I''ve looked at many diamonds online and put a lot of numbers into the Holloway Cut Adviser. Interesting, each time the diamonds always seemed to get an excellent in every category but spread. What must a diamond break possess to break into this elusive excellent spread level?

Does it have to do with having a crown angle of say 34.7 instead of the perfect 34.5 and consequently the diamond has more mass that it should for it''s particular diameter?

 

[ChunkyCushionLover]

Depth 60.3% and less doesn''t matter what crown and pavillion angles.

 

[yssie]

hm... yup, limit is 60.3



Don't restrict yourself to HCA ex-spread stones only, though

 

[diagem]

Date: 3/11/2010 5:37:56 PM
Author: ChunkyCushionLover
Depth 60.3% and less doesn''t matter what crown and pavillion angles.

The title reads: "How does a diamond reach the elusive excellent in spread?"

Is <60.3% dependant or independant of the overall cut grade?

 

[FB.]

As above; 60.3% or less depth. It''s just a number chosen by the HCA developer as the cut-off point. Maybe if HCA was developed again, they''d choose 60.2%, or 60.4%.

In the real world, the difference between a HCA "EX" with 60.3% and a HCA "VG" with 60.4% would be so miniscule as to not be worth bothering about.
I have a 33C/41P/59T/60.5D that falls just 0.2 outside of HCA''s quadruple "EX", but it doesn''t cause me to lose any sleep.

Generally speaking, rough diamonds give greater yields when cut into deep stones - hence the "steep deep" with a depth around 62.3%.
To cut a diamond shallower (therefore less pavilion weight and relatively larger width for its depth) requires wasting a lot more of the rough. Lost rough is undesirable and you would expect to have to pay extra for such a stone, to compensate the cutter for having to waste so much.
Also, most stones in the 60.3% or less depth range tend to have deep pavilions, flat crowns and large tables. Great for maximising yield, but can negatively affect the "life" and sparkle that the stone would show.

 

[ChunkyCushionLover]

Date: 3/11/2010 6:14:24 PM
Author: DiaGem

Date: 3/11/2010 5:37:56 PM
Author: ChunkyCushionLover
Depth 60.3% and less doesn''t matter what crown and pavillion angles.

The title reads: ''How does a diamond reach the elusive excellent in spread?''

Is <60.3% dependant or independant of the overall cut grade?

Independant. Not my opinion that is the output from the HCA.

 

[diagem]

Date: 3/11/2010 7:03:34 PM
Author: ChunkyCushionLover

Date: 3/11/2010 6:14:24 PM
Author: DiaGem

Date: 3/11/2010 5:37:56 PM
Author: ChunkyCushionLover
Depth 60.3% and less doesn''t matter what crown and pavillion angles.

The title reads: ''How does a diamond reach the elusive excellent in spread?''

Is <60.3% dependant or independant of the overall cut grade?

Independant. Not my opinion that is the output from the HCA.

I''d take it as "not your opinion", too simple

.