Find your diamond
Find your jewelry
shape
carat
color
clarity

Help! GIA VG Cut with high HCA Score

Status
Not open for further replies. Please create a new topic or request for this thread to be opened.

fashionangel

Rough_Rock
Joined
Aug 1, 2008
Messages
49
I''m considering this 1.24 Ct, D VS2 stone.

Cut/Polish/Symmetry : VG
Flu: None
Girdle: VT to Med
Table: 58
Depth: 59.1
Crown Angle: 32.0
Pavillion Angle: 41.2
Cutlet: None

The HCA score for this stone is 1.6 and it falls within the GIA EX candidate range. I was set on buying a GIA EX cut diamond until I came across one that has high HCA score (around 4). Then I learnt from this forum that GIA VG cut can actually be as good or better than a EX Cut one. Is this a nice stone that has fire & sparkles? What makes this diamond a VG cut rather than a EX cut? Please share your opinions! Thanks.
 

Sponsored By:

Lorelei

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
42,064
Date: 10/4/2009 11:26:24 AM
Author:fashionangel
I'm considering this 1.24 Ct, D VS2 stone.

Cut/Polish/Symmetry : VG
Flu: None
Girdle: VT to Med
Table: 58
Depth: 59.1
Crown Angle: 32.0
Pavillion Angle: 41.2
Cutlet: None

The HCA score for this stone is 1.6 and it falls within the GIA EX candidate range. I was set on buying a GIA EX cut diamond until I came across one that has high HCA score (around 4). Then I learnt from this forum that GIA VG cut can actually be as good or better than a EX Cut one. Is this a nice stone that has fire & sparkles? What makes this diamond a VG cut rather than a EX cut? Please share your opinions! Thanks.
The very thin girdle will get at best GIA VG so that will be the reason. If you could get an Idealscope image for the diamond if it is sold online that would be very helpful and tell us more about the cut, it could be a nice looking diamond which is geared more towards brilliance than fire due to the slightly shallow crown angle. Also check that the very thin area of the girdle isn't a durability issue by checking with a vendor or an appraiser, if the very thin part only measures in the microns or covers a small portion of the diamond then it could be fine, but best to check always.

Can you post the diameter in MM too please and for completeness, the star and lower girdle facet percentages?
 

strmrdr

Super_Ideal_Rock
Joined
Nov 1, 2003
Messages
23,295
VT girdle with a shallow crown is not a good combination for durability.
The only way I would consider it if it was going in a protected setting and the vt part was small.
 

fashionangel

Rough_Rock
Joined
Aug 1, 2008
Messages
49
Hi Lorelei, here''s the extra info u asked for.

7.05x7.10x4.18mm
Star length: 55%
Lower half: 75%

I''m also considering the below diamond which has v high HCA score of 0.8:



1.26Ct DVS2
7.02x7.06x4.23mm
Cut/Polish: VG
Symmetry: EX
Flu: None
Table: 57%
Depth: 60.1%
Crown: 33.5
Pavillion: 40.8
Star length: 50%
Lower half: 85%
Cutlet: None
Gridle: T-Med faceted 2.5%

Please let me know you comments! Thanks a lot.

 

Lorelei

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
42,064
Date: 10/4/2009 9:42:35 PM
Author: fashionangel




Hi Lorelei, here's the extra info u asked for.

7.05x7.10x4.18mm
Star length: 55%
Lower half: 75%





I'm also considering the below diamond which has v high HCA score of 0.8:







1.26Ct DVS2
7.02x7.06x4.23mm
Cut/Polish: VG
Symmetry: EX
Flu: None
Table: 57%
Depth: 60.1%
Crown: 33.5
Pavillion: 40.8
Star length: 50%
Lower half: 85%
Cutlet: None
Gridle: T-Med faceted 2.5%





Please let me know you comments! Thanks a lot.

Thanks! This one looks good, quite long lower girdle facets/ lower halves so ask for an Idealscope image if you can, the arrows on this diamond will be quite splintery with sharp, bright light flashes as a result, is that ok with you? Would be with me as I love long thin arrows but they aren't to everyone's taste. I will post an example photo for you if I can.

Here is the thread, this large diamond has 85% LGF, look at the arrows to see that they are quite thin. The second diamond you posted above has better proportions than the first one, an Idealscope image is the next step.
 

asforhim

Rough_Rock
Joined
Feb 4, 2009
Messages
81
Have you seen the diamond in person? I have a set of 3 ct earrings and one is a VG cut, the other an EX cut. I entered the info into the HCA and the Ex cut gets a 5 and the VG cut gets a 1.3.... I absolutely cannot tell the difference visually between the stones. I have shown them to a GIA appraiser friend of mine and he also cannot tell the difference visually.

I don''t know which characteristic makes the EX cut have a higher number and the VG have a lower number, but I wouldn''t judge the cut quality soley based on the HCA advisor.
 

Lorelei

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
42,064
Date: 10/5/2009 9:53:14 AM
Author: asforhim
Have you seen the diamond in person? I have a set of 3 ct earrings and one is a VG cut, the other an EX cut. I entered the info into the HCA and the Ex cut gets a 5 and the VG cut gets a 1.3.... I absolutely cannot tell the difference visually between the stones. I have shown them to a GIA appraiser friend of mine and he also cannot tell the difference visually.

I don''t know which characteristic makes the EX cut have a higher number and the VG have a lower number, but I wouldn''t judge the cut quality soley based on the HCA advisor.
Probably the Ex cut diamond has what we call steep deep crown and pavilion angles, that will often give a high HCA score.
 

fashionangel

Rough_Rock
Joined
Aug 1, 2008
Messages
49
No i have not seen the diamonds in person but i''m asking for idealscope images now. So is it safe to say that a diamond with GIA EX cut and a low HCA score (less than 2) is a very well cut diamond with excellent fire & brilliance?
 

Lorelei

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
42,064
Date: 10/5/2009 9:39:28 PM
Author: fashionangel
No i have not seen the diamonds in person but i''m asking for idealscope images now. So is it safe to say that a diamond with GIA EX cut and a low HCA score (less than 2) is a very well cut diamond with excellent fire & brilliance?
It is safe to say such a diamond is worth further investigation!
 

fashionangel

Rough_Rock
Joined
Aug 1, 2008
Messages
49
And I found 1 more diamond 1.35ct, E, VS2 with triple EX. I don''t have the detailed spec here but it has a low HCA score too. Based on the idealscope is this the best one? Please comment on these 3 diamonds. Thanks.

1.35 EVS2.jpg
 

haagen_dazs

Brilliant_Rock
Joined
Sep 2, 2009
Messages
781
Date: 10/4/2009 9:42:35 PM
Author: fashionangel
Hi Lorelei, here''s the extra info u asked for.


7.05x7.10x4.18mm

Star length: 55%

Lower half: 75%
is it right to say that due to the shallow crown and thin girdle, that diamond has a very large spread for a 1.2ct at 7.05mm ?
 

Lorelei

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
42,064
Date: 10/9/2009 12:19:29 AM
Author: fashionangel
And I found 1 more diamond 1.35ct, E, VS2 with triple EX. I don't have the detailed spec here but it has a low HCA score too. Based on the idealscope is this the best one? Please comment on these 3 diamonds. Thanks.
2 or 3 look good, the optical symmetry isn't top notch on either but if that doesn't bother you with the patterning not being perfect then thats fine, can you post all the details for the last diamond please? Number 2 has long lower girdle facets which gives a " sharp" flash when the diamond sparkles, I particularly like that in a diamond but it depends on personal taste.

Mark, a 1.24 ct diamond should measure a little under 7mm so it is spreading a little large for the weight.
 

Stone-cold11

Super_Ideal_Rock
Joined
Sep 9, 2008
Messages
14,069
Date: 10/9/2009 1:04:48 AM
Author: haagen_dazs
is it right to say that due to the shallow crown and thin girdle, that diamond has a very large spread for a 1.2ct at 7.05mm ?
Optimal spread for a 1.24c should be around 6.93mm
 

fashionangel

Rough_Rock
Joined
Aug 1, 2008
Messages
49
Date: 10/9/2009 4:29:51 AM
Author: Lorelei

2 or 3 look good, the optical symmetry isn''t top notch on either but if that doesn''t bother you with the patterning not being perfect then thats fine, can you post all the details for the last diamond please? Number 2 has long lower girdle facets which gives a '' sharp'' flash when the diamond sparkles, I particularly like that in a diamond but it depends on personal taste.

Mark, a 1.24 ct diamond should measure a little under 7mm so it is spreading a little large for the weight.
Lorelei can you pls explain further what the highlighted means? when u say the diamond gives a sharp flash when it sparkles does it means it has more fire & brilliance? thanks a lot.

Here''s the details for the last diamond 1.35 Ct E, VS2, GIA triple Ex
Measurements: 7.07 - 7.13 x 4.40 mm
Depth: 62.0%
Table: 56%
Crown Angle: 35.0¢X
Crown Height: 15.5%
Pavilion Angle: 40.8¢X
Pavilion Depth: 43.5%
Star length: 50%
Lower Half: 80%
Girdle: Thin to Medium, Faceted (3.0%)
Culet: None
 

ChunkyCushionLover

Ideal_Rock
Joined
Jun 21, 2009
Messages
2,463
Date: 10/9/2009 10:52:57 AM
Author: fashionangel

Date: 10/9/2009 4:29:51 AM
Author: Lorelei

2 or 3 look good, the optical symmetry isn''t top notch on either but if that doesn''t bother you with the patterning not being perfect then thats fine, can you post all the details for the last diamond please? Number 2 has long lower girdle facets which gives a '' sharp'' flash when the diamond sparkles, I particularly like that in a diamond but it depends on personal taste.

Mark, a 1.24 ct diamond should measure a little under 7mm so it is spreading a little large for the weight.
Lorelei can you pls explain further what the highlighted means? when u say the diamond gives a sharp flash when it sparkles does it means it has more fire & brilliance? thanks a lot.

Here''s the details for the last diamond 1.35 Ct E, VS2, GIA triple Ex
Measurements: 7.07 - 7.13 x 4.40 mm
Depth: 62.0%
Table: 56%
Crown Angle: 35.0¢X
Crown Height: 15.5%
Pavilion Angle: 40.8¢X
Pavilion Depth: 43.5%
Star length: 50%
Lower Half: 80%
Girdle: Thin to Medium, Faceted (3.0%)
Culet: None
I am sure Lorelei will answer too but the answer is as follows:

1) Optical symmetry refers to the the symmetry of the light return exhibited by the diamond. In the case of #2 there are some darker contrast zones on either side of the arrows on the right side of the diamond that do not appear as dark on the left side of the diamond. Thus the light return seen is not perfectly symmetrical.

2) With a long Lower Half % the arrows get thinner. The long thin arrows are areas of contrast and will give sharp fire and sparkle at certain angles. To some viewers they like the "thin slivery arrows" and the splintery flashes of fire being shown. To others they like fatter shorter arrows which give off broader bigger but shorter flashes of light. For a video comparison of thin versus fat arrows http://www.vimeo.com/6285855. For some they want even bigger flashes of light and go for an Old European Cut http://www.vimeo.com/6524814.
 

Lorelei

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
42,064
Date: 10/9/2009 11:57:10 AM
Author: ChunkyCushionLover





Date: 10/9/2009 10:52:57 AM
Author: fashionangel






Date: 10/9/2009 4:29:51 AM
Author: Lorelei

2 or 3 look good, the optical symmetry isn't top notch on either but if that doesn't bother you with the patterning not being perfect then thats fine, can you post all the details for the last diamond please? Number 2 has long lower girdle facets which gives a ' sharp' flash when the diamond sparkles, I particularly like that in a diamond but it depends on personal taste.

Mark, a 1.24 ct diamond should measure a little under 7mm so it is spreading a little large for the weight.
Lorelei can you pls explain further what the highlighted means? when u say the diamond gives a sharp flash when it sparkles does it means it has more fire & brilliance? thanks a lot.

Here's the details for the last diamond 1.35 Ct E, VS2, GIA triple Ex
Measurements: 7.07 - 7.13 x 4.40 mm
Depth: 62.0%
Table: 56%
Crown Angle: 35.0¢X
Crown Height: 15.5%
Pavilion Angle: 40.8¢X
Pavilion Depth: 43.5%
Star length: 50%
Lower Half: 80%
Girdle: Thin to Medium, Faceted (3.0%)
Culet: None
I am sure Lorelei will answer too but the answer is as follows:

1) Optical symmetry refers to the the symmetry of the light return exhibited by the diamond. In the case of #2 there are some darker contrast zones on either side of the arrows on the right side of the diamond that do not appear as dark on the left side of the diamond. Thus the light return seen is not perfectly symmetrical.

2) With a long Lower Half % the arrows get thinner. The long thin arrows are areas of contrast and will give sharp fire and sparkle at certain angles. To some viewers they like the 'thin slivery arrows' and the splintery flashes of fire being shown. To others they like fatter shorter arrows which give off broader bigger but shorter flashes of light. For a video comparison of thin versus fat arrows http://www.vimeo.com/6285855. For some they want even bigger flashes of light and go for an Old European Cut http://www.vimeo.com/6524814.
Good write up CCL!

When optical symmetry is referred to fashionangel, it means the quality and symmetry of the arrow patterning which is the result of the internal reflections caused by precision cutting and of the alignment of the faceting etc of a diamond. This is done preferably with images from a h&a viewer or Idealscope images. It also refers to hearts which can be viewed on the diamond face down but as the diamonds aren't sold as h&a we needn't be concerned with that in this case. As you can see from the images, the arrows aren't quite symmetrical which isn't an issue with these diamonds as the proportions are good in diamonds 2 and 3 and they aren't sold as h&a.

So in a nutshell, physical symmetry is the lab graded symmetry, the grading on how well the facets, table, culet etc align. Optical symmetry is the study of the internal reflection patterning of the stone.

Check out this thread too on
 

Lorelei

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
42,064
As they say and I believe, a picture is worth a thousand words, so here is an image of a diamond with superior optical symmetry for you fashionangel. Compare this image with the ones of the diamonds you are considering and you will see the difference in optical symmetry. Do remember though that unless you want a diamond with top optical symmetry that there is nothing wrong with diamonds 2 and 3 having optical symmetry which isn't perfect, both should be lovely diamonds.

IS_AGS-1040372120007.jpg
 

Lorelei

Super_Ideal_Rock
Premium
Joined
Apr 30, 2005
Messages
42,064
Date: 10/10/2009 11:27:21 AM
Author: fashionangel
I think I'm going to buy 1 of these diamonds. Is no.3 the best choice?
Both 2 and 3 look good, number 2 might be geared a little more towards brilliance than fire due to the angle configuration but either should be great looking diamonds - also depends on whether you prefer a D or E - there won't be any visible difference ( at least I can't tell between these grades in person) for colour. The second also has longer lower girdle facets which might make a little difference in performance as I mentioned previously, you can notice a sharp flash effect from such diamonds. So it depends on your preferences, they are both good propositions.
 
Status
Not open for further replies. Please create a new topic or request for this thread to be opened.
Be a part of the community It's free, join today!

JEWELRY BLOG

Need Something Special?

Get a quote from multiple trusted and vetted jewelers.

Holloway Cut Advisor



Diamond Eye Candy

Click to view full-size image.
Top