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H&A Failed HCA

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jake1

Rough_Rock
Joined
Aug 24, 2007
Messages
5
Reposted again with proper title.

Although the certified H+A stone looks gorgeous, has a Megascope Cert showing Excellent for Brilliance+Fire and Ideal for Scint, it scored a disappointig 3.5 on the HCA.
Any comments?
Here''re the stats:
RB .97CT
D
VS1
6.36 x 6.35 x 3.94
Depth 61.9%
Table 56.5%
Girdle Sl thick
Crown angle 35
Pav angle 41.2
culet .1%



 
Joined
Jun 5, 2007
Messages
1,236
well, its not really FAILING, and again, who said it is a Hearts and Arrows.

that doesn't always mean what you would think that it should mean

also, Hearts and arrows is not the same thing as light performance, and the HCA is based on light performance.
 

MichelleCarmen

Super_Ideal_Rock
Joined
Feb 8, 2003
Messages
15,880
Have you seen the stone under a H&A viewer to verify it is truely as it is claimed to be? Who certified it?
 

aljdewey

Ideal_Rock
Joined
Nov 25, 2002
Messages
9,170
Date: 9/30/2007 10:41:58 PM
Author:jake1


Reposted again with proper title.

Although the certified H+A stone looks gorgeous, has a Megascope Cert showing Excellent for Brilliance+Fire and Ideal for Scint, it scored a disappointig 3.5 on the HCA.
Any comments?
Here're the stats:

RB .97CT
D
VS1
6.36 x 6.35 x 3.94
Depth 61.9%
Table 56.5%
Girdle Sl thick
Crown angle 35
Pav angle 41.2
culet .1%

1. The diamond didn't "fail"; it scored a very good. Very good is still above average.....just not superlative.

2. The diamond does appear to fall within GIA-EX parameters, but outside of AGS0 parameters.

3. The HCA Cut Advisor is a tool to help predict the likelihood for top performance. Further, it's not a selection tool; it's best used to help eliminate likely poor performers. In any case, it predicts based on a few measurements of the stone but not through evaluating the actual stone itself. For that reason, I'd give much more weight to reports generated on that actual stone then on a sight-unseen tool.

4. H&A isn't a uniform term. What one shop calls H&A, another would reject. As such, it really depends on who is claiming it's an H&A.

5. H&A speaks to precision of the pattern; it doesn't speak to light performance.....which are somewhat related, but not necessarily interchangeable.
 

jake1

Rough_Rock
Joined
Aug 24, 2007
Messages
5
Yes, atually saw the H&A under the H&A viewer.
The stone came with a H&A certificate with a laser engraved number.
I have since read that the HCA calculation does not take the H&A attributes into account which may account for the 3.5 result.
Thanks for your comments.
 

kev1234

Rough_Rock
Joined
Sep 29, 2007
Messages
13
Date: 9/30/2007 11:10:14 PM
Author: aljdewey

Date: 9/30/2007 10:41:58 PM
Author:jake1



Reposted again with proper title.

Although the certified H+A stone looks gorgeous, has a Megascope Cert showing Excellent for Brilliance+Fire and Ideal for Scint, it scored a disappointig 3.5 on the HCA.
Any comments?
Here''re the stats:


RB .97CT
D
VS1
6.36 x 6.35 x 3.94
Depth 61.9%
Table 56.5%
Girdle Sl thick
Crown angle 35
Pav angle 41.2
culet .1%

1. The diamond didn''t ''fail''; it scored a very good. Very good is still above average.....just not superlative.

2. The diamond does appear to fall within GIA-EX parameters, but outside of AGS0 parameters.

3. The HCA Cut Advisor is a tool to help predict the likelihood for top performance. Further, it''s not a selection tool; it''s best used to help eliminate likely poor performers. In any case, it predicts based on a few measurements of the stone but not through evaluating the actual stone itself. For that reason, I''d give much more weight to reports generated on that actual stone then on a sight-unseen tool.

4. H&A isn''t a uniform term. What one shop calls H&A, another would reject. As such, it really depends on who is claiming it''s an H&A.

5. H&A speaks to precision of the pattern; it doesn''t speak to light performance.....which are somewhat related, but not necessarily interchangeable.

Agreed. H&A refers to the symmetry of the cut. There are many other parameters that may affect the performance.
 
Joined
Jun 5, 2007
Messages
1,236
Date: 9/30/2007 11:10:30 PM
Author: jake1
Yes, atually saw the H&A under the H&A viewer.

The stone came with a H&A certificate with a laser engraved number.

I have since read that the HCA calculation does not take the H&A attributes into account which may account for the 3.5 result.

Thanks for your comments.


I would advise using caution at this point, as you seem to be misunderstanding a few things.

the first thing to establish is understanding that a certificate doesn''t necessarily mean anything. I could right you a certificate saying that such and such is a diamond and is hearts and arrows, but who am I to decide? It might just be a piece of quartz, how to tell. well, there are rules and regulations that would get me in trouble if it wasn''t a diamond. but if it isn''t a hearts and arrows...well, nobody is going to be getting in any trouble for that one. So, WHO or WHAT company gave you the "certification" of hearts and arrows, and how do you know that it is, did you see the hearts image yourself? If not do you have a picture.

heck, at this point we don''t even know who gave you the color and clarity grades, or who gave you the angles--some sources site angles with greater accuracy than others.

But the most important thing you seem to be confusing is--light performance trumps Hearts.

Hearts it neat and might mean something in its own right, but if you want a truly beautiful diamond (by common MRB standards, obviously everyone defines beauty in their own way) then light performance TRUMPS hearts. you can flip your loose diamond upside down bust out your scope and look at your hearts all day long, but once it is set if your diamond isn''t returning light properly its going to look pretty crappy, and as we said above, the hearts DO NOT cause for the diamond to return light, there is under some circumstances a relationship, but being "hearts and arrows" does not mean you are getting top of the line light performance.

Not to say this diamond is bad, it might be awesome though I personally woudl aim for specs more inline with AGS0 unless I had a particular reason to go Steep/Deep, but in truth right now there are way too many questions in the air to make any real decisions about this one.
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
18,423
Date: 9/30/2007 11:10:30 PM
Author: jake1
Yes, atually saw the H&A under the H&A viewer.
The stone came with a H&A certificate with a laser engraved number.
I have since read that the HCA calculation does not take the H&A attributes into account which may account for the 3.5 result.
Thanks for your comments.
If the cert is GIA, they do not grade the H&A''s - they simply engrave what ever they are asked to engrave on the girdle - there are plenty of very bad examples of H&A''s with gIA engraved H&A''s
 
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