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HCA scores under 1.0

Vegasvick

Rough_Rock
Joined
Nov 8, 2020
Messages
20
so i've gotten sucked into the world of ACA stones from whiteflash after joining this forum, the one thing i was a bit confused about was that on the HCA tool alot of the ACA stones score 0.9.

on the tool it says these are best for pendants and earrings as they appear dark. I'm a bit confused why pay such a premium for these stones, shouldn't they be scoring in the mid 1's..... am i missing something ?


also does whiteflash ever run promos or codes ?
 

Karl_K

Super_Ideal_Rock
Trade
Joined
Aug 4, 2008
Messages
10,821
Not every stone under 1 has issues and the latest hca update gives a bonus for some things which results in a bunch that would have scored over 1 to go under 1.
For example an ACA now scoring .9 would have scored 1.1 before the update.
 

Texas Leaguer

Ideal_Rock
Trade
Joined
Jul 27, 2009
Messages
3,338
Like any other tool, the HCA is useful if you understand it's limitations. Trying to do too much with any tool is likely to be counterproductive.

The primary value of the HCA is filtering diamonds out of consideration because their basic proportions -table percentage, crown angle, and pavilion angle- do not work together in an optimal way. It is most helpful when other analysis such as advanced images are not available.

The HCA relies on averaged and rounded inputs from lab reports. It cannot perform any kind of actual 3D analysis.

The AGSL light performance system on the other hand involves sophisticated computerized light ray tracing of a 3D model of the diamond, measuring the essential components of brightness, leakage, contrast, and fire. A diamond cannot receive a grade of Ideal if there are meaningful defictis in any of these factors.

Head shadow, or obstruction, is specifically calculated in this system, not only face-up but from a range of tilt angles, alleviating the concern that a diamond will be dark when observed at normal viewing distance.

That said, there is also a small range of AGSL Ideal diamonds that do not meet all the criteria that prosumers have come to expect. That is where the concept of 'super ideal' comes in. And that determination is made by evaluating various criteria over and above what is contained in an AGSL report.
 

Vegasvick

Rough_Rock
Joined
Nov 8, 2020
Messages
20
Like any other tool, the HCA is useful if you understand it's limitations. Trying to do too much with any tool is likely to be counterproductive.

The primary value of the HCA is filtering diamonds out of consideration because their basic proportions -table percentage, crown angle, and pavilion angle- do not work together in an optimal way. It is most helpful when other analysis such as advanced images are not available.

The HCA relies on averaged and rounded inputs from lab reports. It cannot perform any kind of actual 3D analysis.

The AGSL light performance system on the other hand involves sophisticated computerized light ray tracing of a 3D model of the diamond, measuring the essential components of brightness, leakage, contrast, and fire. A diamond cannot receive a grade of Ideal if there are meaningful defictis in any of these factors.

Head shadow, or obstruction, is specifically calculated in this system, not only face-up but from a range of tilt angles, alleviating the concern that a diamond will be dark when observed at normal viewing distance.

That said, there is also a small range of AGSL Ideal diamonds that do not meet all the criteria that prosumers have come to expect. That is where the concept of 'super ideal' comes in. And that determination is made by evaluating various criteria over and above what is contained in an AGSL report.

thank you that was extremely informative and articulated
 

msop04

Ideal_Rock
Premium
Joined
Dec 3, 2011
Messages
9,919
My previous diamond was a 3.33 ct I/SI2 with HCA 0.8 (all four categories graded Excellent). The angles worked such that it was a great performer (CA 34, PA 40.6). It had fire, but mostly lots of white light...

My most recent (and last) upgrade is a 3.38 ct G/VS2 with HCA of 0.9 (all four categories graded Excellent), and it is STUNNING!! TONS of fire! (CA 34.1, PA 40.7) I think the difference is the table of this one is smaller, and it is a bit deeper than my other diamond (at 60.1).

So I do not subscribe to the thought that sub 1.0 HCA diamonds aren't good for rings. Also, I've noticed that sub 1.0 stones tend to be spreadier (larger in diameter). They also tend to get all four "Excellent" on the HCA, whereas >1.0 scores tend to only get "Good" in the spread category.
 

Bonfire

Ideal_Rock
Premium
Joined
Feb 22, 2014
Messages
3,504
My previous diamond was a 3.33 ct I/SI2 with HCA 0.8 (all four categories graded Excellent). The angles worked such that it was a great performer (CA 34, PA 40.6). It had fire, but mostly lots of white light...

My most recent (and last) upgrade is a 3.38 ct G/VS2 with HCA of 0.9 (all four categories graded Excellent), and it is STUNNING!! TONS of fire! (CA 34.1, PA 40.7) I think the difference is the table of this one is smaller, and it is a bit deeper than my other diamond (at 60.1).

So I do not subscribe to the thought that sub 1.0 HCA diamonds aren't good for rings. Also, I've noticed that sub 1.0 stones tend to be spreadier (larger in diameter). They also tend to get all four "Excellent" on the HCA, whereas >1.0 scores tend to only get "Good" in the spread category.

Have you debuted this latest upgrade with us? :?::mrgreen2:
 

Kaycee2018

Brilliant_Rock
Premium
Joined
May 14, 2018
Messages
816
My 2.73ct scores .6 on the HCA (CA 34.5/PA 40.6/Depth 60.8/Table 56). I upgraded from a 1.85ct that scored 1.7 (CA 36/PA 40.6/Depth 61.9/Table 57). I see very slightly more white light return vs. fire, but still plenty of fire and it seems to glow white in even very low light. I think the recent update to the HCA backed off a bit on the blanket “under 1 isn’t good for rings“ concept.
 

meesmom

Brilliant_Rock
Joined
Feb 25, 2015
Messages
653
My previous diamond was a 3.33 ct I/SI2 with HCA 0.8 (all four categories graded Excellent). The angles worked such that it was a great performer (CA 34, PA 40.6). It had fire, but mostly lots of white light...

My most recent (and last) upgrade is a 3.38 ct G/VS2 with HCA of 0.9 (all four categories graded Excellent), and it is STUNNING!! TONS of fire! (CA 34.1, PA 40.7) I think the difference is the table of this one is smaller, and it is a bit deeper than my other diamond (at 60.1).

So I do not subscribe to the thought that sub 1.0 HCA diamonds aren't good for rings. Also, I've noticed that sub 1.0 stones tend to be spreadier (larger in diameter). They also tend to get all four "Excellent" on the HCA, whereas >1.0 scores tend to only get "Good" in the spread category.

U upgraded???:-o Show us please!! ;-)
 

winetime12

Rough_Rock
Joined
Sep 21, 2020
Messages
29
Mine scored 0.8 but got excellent in all four categories. It's a bit shallow at 32 CA and depth 59.5% which probably explains the score (but the steep 41 PA balances it out). Because of this it also faces up big for a 1.0ct. It isn't dark at all even up close.

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48576939-0BD5-4AB2-8FE2-8B2423395403.png
 

La2020

Shiny_Rock
Joined
Nov 15, 2020
Messages
298
Mine scored 0.9 and plenty of fire (34.9 CA, 40.6 PA, 54 Table, 62.6 depth)! I love it as a ring!
 
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