What exactly does the HCA score tell me?

[BigToque]

It says that if you have a score under 2, then you have eliminated the chance of being a poor performer.

Is a lower number better? not really better or worse but just different?

Ex. .5 vs 1.5 - which would be a nicer stone? Would you want to find something at 1.0, or would you always want the number to be as close to zero as possible?

 

[belle]

all stones are going to have different 'personalities' depending on many factors including, but not limited to, the relationship between crown and pavilion angles. a stone with a score of .5 will look different from a stone with a score of 1.5, though we may not actually perceive these differences. a score of less than 2.0 is considered 'ideal' and one score is not better than another once you go under 2.
no, the goal is not to try to get closer to zero.

 

[strmrdr]

A lot of diamonds that score in the aprox .7 and under range are combinations better suited for pendants and earrings than rings.
The steep/shallow combinations tend to score in that range.
That isnt to say that all diamonds that score under .7 are steep/shallow or that a steep/shallow cant score higher than that.

 

[MaybeDayze]

Belle -

I understand that you can''t really split hairs, a .5 isn''t necessarily better than a 1.4. It''s a matter or preference.

Do we know what kinds of properties a .5 will have versus a 1.4?
Is a .5 more firey whereas a 1.4 more brilliant? Do we know what score will have which properties?
How does that work exactly? What am I missing? I feel like I''m not understanding something obvious.

Anyone who knows feel free to answer, I''ve been wondering this for a while.

MarLO

 

[BigToque]

Date: 7/19/2005 1:10:00 PM
Author: MarLoRey
Belle -

Do we know what kinds of properties a .5 will have versus a 1.4?
Is a .5 more firey whereas a 1.4 more brilliant? Do we know what score will have which properties?

This is what I''m wondering about... what exactly is the score telling me about the diamond?

 

[Regular Guy]

Oofah!

 

[Murph]

BigToque,
In general the HCA is viewed as a tool to help weed out poor performing stones.

I get frustrated with it because the numbers you input (crown and pav angles...) are generated by machines that have too much variance for a theoretical tool like the HCA. Most vendors deffer to the AGS report as the ultimate authority, but what are you supposed to do when even the AGS admits that there is a margin of accuracy of 0.1 to 0.2degrees on any angle (Sarin tolerances). Try inputing numbers into the HCA, first with a 41.1 pav then with a 40.9. Same stone....2 set of data...which do you choose?

Data set #1: Cr. 34.2 Pav 41.1 Tab 56 Depth 60.7...............HCA 2.2
Data set #2: Cr. 34.2 Pav 40.9 Tab 56 Depth 60.7...............HCA 1.2


Cheers,
Murph

 

[belle]

Date: 7/19/2005 1:31:10 PM
Author: Murph
BigToque,
In general the HCA is viewed as a tool to help weed out poor performing stones.

I get frustrated with it because the numbers you input (crown and pav angles...) are generated by machines that have too much variance for a theoretical tool like the HCA. Most vendors deffer to the AGS report as the ultimate authority, but what are you supposed to do when even the AGS admits that there is a margin of accuracy of 0.1 to 0.2degrees on any angle (Sarin tolerances). Try inputing numbers into the HCA, first with a 41.1 pav then with a 40.9. Same stone....2 set of data...which do you choose?

Data set #1: Cr. 34.2 Pav 41.1 Tab 56 Depth 60.7...............HCA 2.2
Data set #2: Cr. 34.2 Pav 40.9 Tab 56 Depth 60.7...............HCA 1.2


Cheers,
Murph

murph,
you are correct, there is a margin of accuracy of up to .2
keep in mind however, that the number on the report is the average of all 8 pavilion angles.

 

[Regular Guy]

Murph,

While Garry H has perhaps gotten on the verge of being bored with this topic, I think lostdog has several posts, including probably his introduction to this board with this post, that speaks to your issues.

One way of looking at it, by analogy, is like going to a tailor when you find your sleeves are a bit short. You tell him, with my arms down like this, my sleeve is too short. Of course, your tailor''s response...

don''t hold your arms that way.