Always go with best HCA?

[eric57791]

Using the HCA for some rounds in the 1.2 range there are two stones that are similar but the HCA score is 0.7 for a 1.225 ct stone that isn''t H&A or ACA, while the othere I am looking at scores higher at 1.1 for a H&A/ACA 1.218 ct. This doesn''t make sense to me that the H&A/ACA scores higher (worse) on the cut advisor... can someone explain?

 

[chrono]

All the scores of HCA below 2 are great stones. It doesn''t mean a HCA = 0 stone is better than a HCA = 2 stone. The HCA is just a tool for weeding out bad looking stones. After that, other tools come into play to fine tune your selection. This is where the Idealscope and ASET comes into play.

 

[eric57791]

Thanks. What are possible reasons for the lower HCA score not being considered ACA on Whiteflash or H&A?

 

[chrono]

I'm not sure if I understand you question but I'll give it a shot.

Remember, the HCA is a WEEDING tool, not a final selection too.
ACAs are cut to stringent standards, not just for optical symmetry and H&A pattern, but also for optical performance. It is very possible for a diamond to have a HCA score below 2, yet not have a H&A pattern.

Summary:
All ACAs will be true H&A, and have scores below HCA 2 AND awesome Idealscope picture.
NOT all diamonds with HCAs below 2 will have H&A pattern (and I'm not even talking a true precision cut H&A pattern), and not all will have an awesome Idealscope picture.

 

[kcoursolle]

Date: 8/3/2007 2:02:49 PM
Author: eric57791
Thanks. What are possible reasons for the lower HCA score not being considered ACA on Whiteflash or H&A?

Strong flourescence, girdle variations, symmetry issues, etc. Brian looks at all of the ACA candidates and weeds any that might even just have tiny differences.

 

[Lorelei]

Date: 8/3/2007 1:42:38 PM
Author:eric57791
Using the HCA for some rounds in the 1.2 range there are two stones that are similar but the HCA score is 0.7 for a 1.225 ct stone that isn't H&A or ACA, while the othere I am looking at scores higher at 1.1 for a H&A/ACA 1.218 ct. This doesn't make sense to me that the H&A/ACA scores higher (worse) on the cut advisor... can someone explain?

A score under 2 doesn't mean a diamond looks better than another with the scores you have noted necessarily, it is more of a pass or fail with pass being under 2, not that any score under 2 is better than another. The HCA is a predictor of performance and once you get to scores under 2 such as these ( considered to be cherry) then you need to be evaluating the diamonds on other merits and individual proportions to help your selection. H&A needs to be evaluated by other means, however an ACA is going to be a more or less guaranteed excellent performer! A diamond has to go through rigorous evaluation by experts to be awarded the ACA title.

 

[Garry H (Cut Nut)]

there are conflicting factors - no simple answer to your complex question - many people prefer rings stones to be between 1 and 2.

Read the warning link that comes up after you do a search

 

[Regular Guy]

Date: 8/3/2007 1:42:38 PM
Author:eric57791
... can someone explain?

I drew this earlier, but took till later to modify the size.

...and, then Garry had to come along and give you the answer. I'll try, too, anyway....since 50% of the discussion of HCA has me in it anyway.

My younger son plays a computer game where he's travelling in some land. The map of the land is on the left. He drives and based on the direction he points the pointer to, the object "goes" in that direction.

I think there is some relationship between HCA and this direction...with respect to the diamond/object. A direction and spatial aspect is noted...but with respect to the actual thing...you are less clear where you are. For more clarity, see IS or ASET. Also, if the spot in the object is dead center with where you want your HCA score to be, the greater the likelihood that the actual object isn't misrepresented.

Sorry to add confusion. Was just an idea...

 

[Garry H (Cut Nut)]

Eric you just got Ira''ed