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Which one sparkles more? Do I trust my eye or HCA?

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TripleC

Rough_Rock
Joined
Jun 14, 2009
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I''m pretty close to figuring out what I want but I just came across a big conflict. When looking at some diamonds last week, I was comparing an H/SI1, G/SI1, and E/SI1. All three stones are ~2ct, Ideal cut, Ex/Ex polish and symmetry, have no cutlet or fluorescence.

Obviously, the E looked the best in terms of color, but it also seemed to sparkle the most. I had pretty much decided on the smaller/more expensive E/SI1 also due to some inclusions in the others. However when I was mulling over my options, I came across this:

H/SI1 HCA score EX/EX/EX/VG - 1.2
table 56%
depth 61.5%
crown 35.5%
pavilion 40.6%

G/SI1 HCA score EX/EX/EX/VG - 1.6
table 56%
depth 62.3%
crown 35%
pavilion 40.8%

E/SI1 HCA score VG/G/G/VG - 3.3
table 56%
depth 62.2%
crown 34.5%
pavilion 41.2%

When I asked about the difference in HCA score, I was told to "trust my eye, the angles are basically the same."

So a few questions:
Will this HCA score affect the value of my diamond?
Given that I''ve seen the diamonds in person, is my eye deceiving me? Was the stone just well polished? or could it be that the one with the 3.3 HCA score sparkled more than the 1.2?


If I never used the HCA calculator I would have purchased this diamond, but the HCA has me questioning my own judgement and whether it truly does "sparkle" as much or more than the others.

Thanks for any help.
 
Did you compare all 3 diamonds under different conditions and not just under jewelry store lighting?

Also what is the lower girdle facet number?
 
Date: 7/1/2009 2:21:02 PM
Author:TripleC
I'm pretty close to figuring out what I want but I just came across a big conflict. When looking at some diamonds last week, I was comparing an H/SI1, G/SI1, and E/SI1. All three stones are ~2ct, Ideal cut, Ex/Ex polish and symmetry, have no cutlet or fluorescence.

Obviously, the E looked the best in terms of color, but it also seemed to sparkle the most. I had pretty much decided on the smaller/more expensive E/SI1 also due to some inclusions in the others. However when I was mulling over my options, I came across this:

H/SI1 HCA score EX/EX/EX/VG - 1.2
table 56%
depth 61.5%
crown 35.5%
pavilion 40.6%

G/SI1 HCA score EX/EX/EX/VG - 1.6
table 56%
depth 62.3%
crown 35%
pavilion 40.8%

E/SI1 HCA score VG/G/G/VG - 3.3
table 56%
depth 62.2%
crown 34.5%
pavilion 41.2%

When I asked about the difference in HCA score, I was told to 'trust my eye, the angles are basically the same.'

So a few questions:
Will this HCA score affect the value of my diamond? No.
Given that I've seen the diamonds in person, is my eye deceiving me? Was the stone just well polished? or could it be that the one with the 3.3 HCA score sparkled more than the 1.2? The angle ranges are not the same and can give veryh different results, I would be most interested in 1 and 2 rather than 3. If you like the last one give it a test drive by looking at it away from any store lights, then you might see the difference.


If I never used the HCA calculator I would have purchased this diamond, but the HCA has me questioning my own judgement and whether it truly does 'sparkle' as much or more than the others. The HCA isn't the be all and end all, it is used for rejection, not selection. I would try to evaluate this last diamond as carefully as you can and compare it with the others to see which looks best.

Thanks for any help.
Click to expand...
 
Girdle #''s

H - thin-med (faceted) 3.0%
G - med-sl thick (faceted) 4.0%
E - med-sl thick (faceted) 3.0%
 
Date: 7/1/2009 2:40:21 PM
Author: TripleC
Girdle #''s

H - thin-med (faceted) 3.0%
G - med-sl thick (faceted) 4.0%
E - med-sl thick (faceted) 3.0%
Click to expand...

Lower girdle facet size not the girdle thickness variation.
 
Date: 7/1/2009 2:33:46 PM
Author: Lorelei
Date: 7/1/2009 2:21:02 PM

Author:TripleC

I''m pretty close to figuring out what I want but I just came across a big conflict. When looking at some diamonds last week, I was comparing an H/SI1, G/SI1, and E/SI1. All three stones are ~2ct, Ideal cut, Ex/Ex polish and symmetry, have no cutlet or fluorescence.


Obviously, the E looked the best in terms of color, but it also seemed to sparkle the most. I had pretty much decided on the smaller/more expensive E/SI1 also due to some inclusions in the others. However when I was mulling over my options, I came across this:


H/SI1 HCA score EX/EX/EX/VG - 1.2

table 56%

depth 61.5%

crown 35.5%

pavilion 40.6%


G/SI1 HCA score EX/EX/EX/VG - 1.6

table 56%

depth 62.3%

crown 35%

pavilion 40.8%


E/SI1 HCA score VG/G/G/VG - 3.3

table 56%

depth 62.2%

crown 34.5%

pavilion 41.2%


When I asked about the difference in HCA score, I was told to ''trust my eye, the angles are basically the same.''


So a few questions:

Will this HCA score affect the value of my diamond? No.

Given that I''ve seen the diamonds in person, is my eye deceiving me? Was the stone just well polished? or could it be that the one with the 3.3 HCA score sparkled more than the 1.2? The angle ranges are not the same and can give veryh different results, I would be most interested in 1 and 2 rather than 3. If you like the last one give it a test drive by looking at it away from any store lights, then you might see the difference.



If I never used the HCA calculator I would have purchased this diamond, but the HCA has me questioning my own judgement and whether it truly does ''sparkle'' as much or more than the others. The HCA isn''t the be all and end all, it is used for rejection, not selection. I would try to evaluate this last diamond as carefully as you can and compare it with the others to see which looks best.



Thanks for any help.
Click to expand...
Click to expand...
So a few questions:

Will this HCA score affect the value of my diamond? No.

Given that I''ve seen the diamonds in person, is my eye deceiving me? Was the stone just well polished? or could it be that the one with the 3.3 HCA score sparkled more than the 1.2? The angle ranges are not the same and can give veryh different results, I would be most interested in 1 and 2 rather than 3. If you like the last one give it a test drive by looking at it away from any store lights, then you might see the difference.



If I never used the HCA calculator I would have purchased this diamond, but the HCA has me questioning my own judgement and whether it truly does ''sparkle'' as much or more than the others. The HCA isn''t the be all and end all, it is used for rejection, not selection. I would try to evaluate this last diamond as carefully as you can and compare it with the others to see which looks best.



Thanks for any help.
Click to expand...

I looked at the stones under incandescent light, fluorescent light, and some window daylight, but didn''t take the stones out in the sun. As I said, I was most impressed by the stone with the lowest score so I''m a bit confused.
 
Here are the lower half lengths:

H/SI 80%
G/SI 75%
E/SI 80%

Here are the lower pavilion heights:

H/SI 42.5%
G/SI 43%
E/SI 43.5%
 
Date: 7/1/2009 2:56:00 PM
Author: TripleC
Here are the lower half lengths:

H/SI 80%
G/SI 75%
E/SI 80%

Here are the lower pavilion heights:

H/SI 42.5%
G/SI 43%
E/SI 43.5%
Click to expand...
Its ok, don't worry about being confused! The girdle facets are all within good range so no concerns there. These can fine tune the personality of the diamond, but I would be more concerned with the overall proportions.

I would do this, ask the seller if you can view the diamond you like best, preferably all 3 away from the store lights in plain daylight to get a more accurate idea of how they look. Also you could try viewing then under a desk in dim light, see if they go " dead" or if the lower scorer you like best does. Really look at each and compare the 2 with the 80% lower girdle facets to see if the 2 stones have something in common in the way they behave that you like. Compare them also with the one with the shorter 75% girdle facets to see how they compare and which type you like best. If in the end you like the E best and you have really given it a good test run, despite the others looking better on paper, maybe it is the one for you.
 
So what you''re saying is, I shouldn''t trust my eye?
2.gif
 
Date: 7/1/2009 3:00:40 PM
Author: TripleC
So what you're saying is, I shouldn't trust my eye?
2.gif
Click to expand...

Yes, I just added that at the bottom of my post! I would say trust your eye cautiously! Also you could buy one of these for $25, an Idealscope that you can take with you and use, they are straightforward to use and to interpret the results. This page explains further.

http://www.ideal-scope.com/cart_zoom_item.asp?Id=2&ShowAdd=Y

http://www.highperformancediamonds.com/index.php?page=education-performance
 
I think you'll be very happy with your E color.

All things being equal, and I would say these cuts are comparable, that
a whiter stone will make you smile for years to come.

Sincerely,
Sugardiamonds
 
I seriously doubt anyone not in the industry can tell the difference between E and G in terms of color.
 
I just got idealscope images...here''s the E SI1 HCA 3.3

E SI1.jpg
 
Here''s the idealscope for the G/SI1...HCA 1.6

GSI1abcd.jpg
 
Well, the IS definitely shows leakage for the E SI.

Maybe you like the leakage effects for the contrast?
 
Date: 7/1/2009 6:56:08 PM
Author: Stone-cold11
Well, the IS definitely shows leakage for the E SI.


Maybe you like the leakage effects for the contrast?
Click to expand...


This makes me trust my eye even less. I''m not quite sure what you mean about how the leakage effects can cause contrast. It seems to me that the G stone has more contrast (black) and more light return (red), so overall, it should stand out more, true?
 
I agree with stone-cold about the leakage in the IS for the E. However, maybe in real life the leakage is not apparent. Make sure to compare the stones under a table, away from direct light to see if the E goes "dark." The other thing I''m wondering -- and others who know more about this than I do, please chime in -- is that maybe what appeals to you about the E is that you like the combination of the long lower girdles (80%) and the E color. I had a stone with similar specs (a D with 81% lower girdle facets) and it was indeed white and sparkly. That may be the visual quality of the stone that is appealing to you, and there''s nothing wrong with that - colorless stones with long lower girdles have a definite zip to them, IMHO. I''d say double-check one more time in a dimly light part of the store to compare the two stones, and if the E still looks good to you, go with that one.
 
Date: 7/1/2009 7:22:18 PM
Author: sarap333
I agree with stone-cold about the leakage in the IS for the E. However, maybe in real life the leakage is not apparent. Make sure to compare the stones under a table, away from direct light to see if the E goes ''dark.'' The other thing I''m wondering -- and others who know more about this than I do, please chime in -- is that maybe what appeals to you about the E is that you like the combination of the long lower girdles (80%) and the E color. I had a stone with similar specs (a D with 81% lower girdle facets) and it was indeed white and sparkly. That may be the visual quality of the stone that is appealing to you, and there''s nothing wrong with that - colorless stones with long lower girdles have a definite zip to them, IMHO. I''d say double-check one more time in a dimly light part of the store to compare the two stones, and if the E still looks good to you, go with that one.
Click to expand...
Ditto. Low light conditions will show the difference the best, especially if you can compare them side by side.
 
Leakage can result in contrast too.

How did you hold the stone when you are viewing it? Is light coming in through the pavilion when you are viewing it?
 
SaraP, thanks for the thought - seems like good reasoning.

Date: 7/1/2009 7:36:08 PM
Author: Stone-cold11
Leakage can result in contrast too.


How did you hold the stone when you are viewing it? Is light coming in through the pavilion when you are viewing it?
Click to expand...

No, the view that convinced me that the E had good light return was when the jeweler/gemologist laid them side by side on the back of her hand between her fingers (as if on a ring). Then with overhead light, it seemed that it was brighter than the G.

I compared them at different angles as well, but probably didn''t look as carefully as I should have under dim light or in daytime light. I was mostly looking at the table view an I imagine that was the angle of the most light entry during my viewing.
 
Table view is correct and that method of comparing diamonds is good, but should not be viewing at such a bright lighting condition.

If you want to view again, try and see if you can notice skin color coming through the pavilion for the E SI1.
 
Yes, see if the sales person will allow you to put the stones between your fingers on the back of your hand and hold them underneath the table. Pay close attention to how the stones perform in that light. You want to check to see if the stone loses its sparkle or if it appears dull and dark (compared to the other stones).

I never understood what seeing skin through the stone meant -- I missed this in my cut tutorial, I guess! Stone-cold, would you explain what it means to see skin through the stone? Thanks!
 
See the images above? You can see the skin color coming through the diamond from the pavilion, under the table. In bright light, this could be mask or mistaken as light return. In open setting, light coming in from the pavilion could be mistaken for light return. In close setting, like bezel, it will go dark unless the inside of the bezel is polish.
 
Oh, that makes perfect sense -- thanks, Stone. I do remember a long-ago post by somebody -- Storm, maybe? -- suggesting that you can wrap a small piece of paper around the stone below the girdle to shut out the light to show you what the stone will look like in a setting that cuts out the light from the sides/bottom (like a bezel).
 
yap, I think that is from storm too, or at least the post I read.
 
The HCA is infallible.
2.gif
Not! Nothing wrong with trusting your eyes.
 
Date: 7/1/2009 8:55:42 PM
Author: Abril
The HCA is infallible.
2.gif
Not! Nothing wrong with trusting your eyes.
Click to expand...

But the IS shows leakage. Maybe he didn't check closely enough, in enough different conditions? Trust your eyes but know what you are seeing.
 
Date: 7/1/2009 8:55:42 PM
Author: Abril
The HCA is infallible.
2.gif
Not! Nothing wrong with trusting your eyes.
Click to expand...

Thanks for all the advice and the articles. I'll definitely have to take a second look under different light variations. You guys seem torn over the HCA and your own eye as well...glad I'm not the only one.
 
When you looked at the stones it is helpful to hold them so minimal light can enter the pavilion - if they are in tweezers this masks the leakage effect.
My experiance is that the E will show dull zones when it is dirty.

But in this case it is being helped by painting - which is an effect that you can read about by searching for Eight star 8* and ACA new line - so the HCA score is probably effectively closer to around 3.
 
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