Ideal cuts -- not ideal?

[librarychickie]

I've been researching "ideal," "hearts & arrows," "preferred" round brilliant cuts, but when I plug their numbers into the HCA, they score 4 and 5. Is that normal? When I go down the vendor's list to the "excellent" and "above average" cuts, the scores get lower; thus, indicating a more brilliant stone. Why would that be?

~LC

 

[stone-cold11]

Case by case. Depends on how the vendor grades their cuts.

Post the grading report.

 

[yssie]

different vendors and different tools define their ideal ranges of proportions differently. Ideal and Ex stones as defined by AGS and GIA respectively also have different top-cut ranges, neither of which are in perfect agreement with the HCA. Go by inspections, videos, photos, numbers - tools and vendor definitions are all non-perfect.

 

[librarychickie]

Here are a couple of reports. I just did a couple of screen shots to get the pertinent information. The 1.59 carat is listed as "preferred and H&A" while the 1.54 is listed as "above average." However, their HCA scores are completely opposite.

 

[Garry H (Cut Nut)]

Here are a couple of reports. I just did a couple of screen shots to get the pertinent information. The 1.59 carat is listed as "preferred and H&A" while the 1.54 is listed as "above average." However, their HCA scores are completely opposite.

GIA dinged the first stone because it has a very thin girdle - and with all those marks near the edge - it may indeed be a risk. But with careful setting and no brick laying it might be a keeper - it is definetly a better set of proportions than the other which is slightly steep deep.

 

[yssie]

cant see lgf on the bottom one, in any case it's likely to show some leakage in the lgfs under the table - whether you personally find it visible/offensive will depend on your vision.

the HCA is a purely binary blunt weeding tool, don't try to select the 'better' score - it is either above or below 2.

 

[risingsun]

Some vendors call their diamonds ideal in a generic sense. This has no real meaning. The only "real" ideal diamonds are those graded by AGS and given the grade of 0 [ideal], which is their highest grade. It is also performance based, rather than parametrically based.