Emerald Cut - Poll (what ya got?????)

[bdazed]

SCENARIO:
Weight = 2.02 carats; Dimensions = 8.72-5.92x4.10mm; Girdle = thin / polished; Depth = 69%;
Table = 77%; Crown = 13%; Pav = 55%; Culet = None

QUESTION: Is there any evidence that a diamond with a depth of ~69% and crown of ~13% on an EC (Emerald Cut) is degraded by a ~77% table? Has anybody experimented with an Ideal-scope or Sarin report to measure the properties of a similar stone?

I have now seen many side-by-side ECs and cannot conclusively say that the ideal dimensions offer a material advantage........ in fact the bad boy profiled above had more fire under sunlight then many others that fall inside the typically "accepted" AGA ranges. Are the AGA publications for ECs a science, a guideline, or folklore? Note: to add to my confusion I see companies like Whiteflash.com selling large tabled stones with otherwise premium properties for over $8k/carat (VS2,G) (reference: http://www.whiteflash.com/emerald/Emerald-cut-diamond-629381.htm)

Should I stick with my visual instincts or holster the crack pipe?????????????????

Let''s get some banter going.....

 

[chrono]

Dave has made it clear on numerous occasions that the AGA cut chart for fancy shaped diamonds is only a guide. It will help sort out most bad cuts and diamonds with inherent flaws. After that, it is up to the buyer (with the help of an independent appraiser) to view the stone to make a final decision.

 

[valeria101]

Vote: Go with your gut instict! Any day!

If in doubt, yu can always use the Gem Adviser (or similar software - the more primitive is free) to model the proportions and find out why they work.

By pen and paper simulation, what you describe can work ''cause of the higher crown - there is simply enough of it to allow crown facets to reflect down onto the pavilion form most viewing angles. With a cut like this, dispersion is produced by light crossing the table facet at acute angles, not by prism effects from crown facets.

If anything gets lost, it would be scintillation, not brilliance or fire.

 

[Hest88]

That higher crown is what makes the biggest difference in my mind. Table size is important, but not as important, I think, than depth or crown height. If depth and crown are perfect then I''d be less concerned about table size.

Still, I prefer a smaller table. Gives it a livelier appearance.

 

[valeria101]

Let's see if a better look at what these proportions look like makes any difference. This is obviously not your stone, but two extreme sets of proportions that should work as visual clues for a range of Ec cuts.

#1. A stone with small table and very high crown (75%depth, 57%table, crown >15%-guess): Link_to_Flash

#2. And another, of the large tabled, flashy variety (69% depth, 71%table, crown say... 7% or so): Link_to_Flash

The second sounds (a diamond "sounds" like it's numbers and "looks like" it's pictures, IMO

) more like your stone. Although 77% table is noticeably more than 71%.

BTW, is there a comment on the GIA cert ? I would expect that stone to have way steep crown angle, and if this gets above 40 degrees, GIA takes notice.