Find your diamond
Find your jewelry
shape
carat
color
clarity

Is HCA really valid?

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

JulieN

Super_Ideal_Rock
Premium
Joined
Jul 25, 2005
Messages
13,324
pav angle is definitely deep, you can see it in the picture.
 

strmrdr

Super_Ideal_Rock
Joined
Nov 1, 2003
Messages
23,295
In that case yes...
here is the picture of the stone....

1105005PIC.JPG
 

strmrdr

Super_Ideal_Rock
Joined
Nov 1, 2003
Messages
23,295
smaller picture...

1105005PIC1.JPG
 

starryeyed

Ideal_Rock
Joined
Nov 6, 2006
Messages
2,398
Looks like the diamond was not level when the picture was taken. It is an EX/EX.
 

avlis

Shiny_Rock
Joined
Oct 21, 2006
Messages
237
i though tthe HCA was about proportions, and the stone mentioned is GIA graded on symetry and polish. this is apples and oranges. GIA doesnt grade "cut"
 

pricescope

Ideal_Rock
Joined
Dec 31, 1999
Messages
8,266
Lovebling,

You can decide for yourself. The diamond has 41.4 degree pavilion -> leakage under the table -> penalty from HCA.

If the stone is set in an open high settings (e.g. 4 prong Tiffany style) you most probably won't see it. If you block the light coming from pavilion (bezel setting, dirt, etc) you should see dark area under the table like on the picture below (diamond C from http://journal.pricescope.com/Articles/37/2/GIA-Excellent-Cut-Grade-Case-Study.aspx).

see also video

 

starryeyed

Ideal_Rock
Joined
Nov 6, 2006
Messages
2,398
Date: 2/13/2007 8:37:43 PM
Author: avlis
i though tthe HCA was about proportions, and the stone mentioned is GIA graded on symetry and polish. this is apples and oranges. GIA doesnt grade ''cut''
Hi Avlis. GIA recently started grading cut. GIA uses "Excellent" for their top grade. This refers to proportions. HCA also deals with proportions, but more in terms of visual performance. Not all GIA "Excellent" cuts earn the coveted "less than 2" on the HCA. Hope this helps.
 

lovebling

Rough_Rock
Joined
Feb 6, 2007
Messages
25
Thank you Pricescope!! Wow, the article and especially the video is very interesting!
 

lovediamond!

Rough_Rock
Joined
Feb 9, 2007
Messages
17

Hello everyone! I wish I had found this forum sooner! I got engaged in Oct '06 and was pretty happy about my diamond until I started reading more on this forum. When I ran my diamond on the HCA, I got a score of 4 Now, that would be fine if the diamond didn't cost a lot, but it was quite expensive considering it's HCA score (~40,000). It was graded by the GIA prior to 2006, but I called and got the crown/pavilion info (see below). When I tried looking at the AGS table, I got a cut grade of 1 (four 1's and two 0's).



What I don't understand is if the cut is so crucial to the performance of the diamond, then why does color and clarity seem to have a greater impact on the price? I mean GIA didn't even have cut info prior to 2006.



I know now that the pavilion angle 41.4 is too steep.

What do you think of my diamond? I guess there's nothing much I can do about it now. Any info would be greatly appreciated!! Thank you!



size 2.01 ct
8.09-8.13 x 5mm
color E
VVS2
table 58%
depth 61.7%
crown angle 33.5
crown height 14%
pavilion angle 41.4
pavilion depth 44%
fluoresence faint
medium girdle
symmetry Ex
polish VG
culet None
 

tanalasta

Shiny_Rock
Premium
Joined
Dec 28, 2006
Messages
323
LoveDiamond

You paid a lot of money for your diamond because it was an E colour, VVS clarity and over 2Ct. Even though your pavillion is a little bit on the deep side, the crown angle being 33.5 does somewhat compensate for this. Colour and clarity have an importance on the price because of rarity and market forces. A D to F colour diamond and a VVS/IF clarity is still very much in high demand, especially in some asian markets and are also highly prized. It may not look ''that much more expensively better'' compared to say a G, SI1 that is eye-clean set in platinum but in the mind and wallet it does!

Have you looked at your diamond''s light performance under an Idealscope? And are you happy with how it looks before you found about the HCA?

If you are, then Garry makes a very good point. After all, he did design the HCA!
 

Ellen

Super_Ideal_Rock
Joined
Jan 13, 2006
Messages
24,426
Date: 2/13/2007 10:23:33 PM
Author: lovediamond!

Hello everyone! I wish I had found this forum sooner! I got engaged in Oct ''06 and was pretty happy about my diamond until I started reading more on this forum. When I ran my diamond on the HCA, I got a score of 4 Now, that would be fine if the diamond didn''t cost a lot, but it was quite expensive considering it''s HCA score (~40,000). It was graded by the GIA prior to 2006, but I called and got the crown/pavilion info (see below). When I tried looking at the AGS table, I got a cut grade of 1 (four 1''s and two 0''s).




Unless you want to try trading it in, I''d try to remember this.
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
15,203
Date: 2/13/2007 10:23:33 PM
Author: lovediamond!

Hello everyone! I wish I had found this forum sooner! I got engaged in Oct ''06 and was pretty happy about my diamond until I started reading more on this forum. When I ran my diamond on the HCA, I got a score of 4 Now, that would be fine if the diamond didn''t cost a lot, but it was quite expensive considering it''s HCA score (~40,000). It was graded by the GIA prior to 2006, but I called and got the crown/pavilion info (see below). When I tried looking at the AGS table, I got a cut grade of 1 (four 1''s and two 0''s).




What I don''t understand is if the cut is so crucial to the performance of the diamond, then why does color and clarity seem to have a greater impact on the price? I mean GIA didn''t even have cut info prior to 2006.
That is an excellent question - the reason is that most of the market either does not know what is good and what is not so good, or tries its hardest to ensure that near enough is good enough. For many years GIA only indicated sym and polish on its reports - and maybe 1/2-2/3rds of all retailers and their diamond buying consumers got to thinking that this must mean the cut is good or bad. Proportions are harder to understand. so the market sells cut cheap.


I know now that the pavilion angle 41.4 is too steep.

What do you think of my diamond? I guess there''s nothing much I can do about it now. Any info would be greatly appreciated!! Thank you!




size 2.01 ct
8.09-8.13 x 5mm
color E
VVS2
table 58%
depth 61.7%
crown angle 33.5
crown height 14%
pavilion angle 41.4
pavilion depth 44%
fluoresence faint
medium girdle
symmetry Ex
polish VG
culet None
 

Beacon

Ideal_Rock
Joined
Jul 14, 2006
Messages
2,037
This topic has puzzled me too from time to time.

Garry, when you look at a GIA excellent cut that has a lowish rating on HCA, say a rating in the mid 3s, do you see a difference, visually, when the item is set in jewelry and being worn?

I am curious if the GIA excellent cuts that don''t make it on HCA are more of a mathmatical problem, or do they actually look poor as jewelry? I am sure you have seen many of these out there and wonder your opinion. Thanks!
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
15,203
Date: 2/14/2007 4:10:12 PM
Author: Beacon
This topic has puzzled me too from time to time.

Garry, when you look at a GIA excellent cut that has a lowish rating on HCA, say a rating in the mid 3s, do you see a difference, visually, when the item is set in jewelry and being worn?

I am curious if the GIA excellent cuts that don''t make it on HCA are more of a mathmatical problem, or do they actually look poor as jewelry? I am sure you have seen many of these out there and wonder your opinion. Thanks!
When I first met Peter Yantzer - director AGS lab- i complained about their 35.8 crown and 41.2 pavilion that was given AGS 000 until 2 years ago (and they are finally closing as a loop hole now). Peter told me that as soon as they had a better system, they would impliment it. He agreed that the steep deep was not so beautiful. I still think they could improve on their current system - but I do not have an answer yet to a better method that a lab could employ, so that is not a criticism.

GIA on the other hand has done bad science and got a bad result, and they are not open to a review - it was made very clear leading up to the GIA Symposium that ''Cut Grading'' was not on the agenda.
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
15,203
Date: 2/14/2007 4:10:12 PM
Author: Beacon
This topic has puzzled me too from time to time.

Garry, when you look at a GIA excellent cut that has a lowish rating on HCA, say a rating in the mid 3s, do you see a difference, visually, when the item is set in jewelry and being worn?

I am curious if the GIA excellent cuts that don''t make it on HCA are more of a mathmatical problem, or do they actually look poor as jewelry? I am sure you have seen many of these out there and wonder your opinion. Thanks!
Sorry - simple answer

They dont look as big
They are not as bright, but can be firey especially in open settings in rings (but lousy for earrings and pendants)
Tthey show dirt very badly and loose a lot more brilliance when dirty compared to tolkowsky or shallower diamonds.
 

Beacon

Ideal_Rock
Joined
Jul 14, 2006
Messages
2,037
Thanks for this information. I am going to get a firsthand look on Friday. I am going to go see a stone that does not rate so well on HCA but am told it is nice.

It''s biggest defect is it''s crown angle I guess. It''s a 59/61.3/34.5/41.2

I don''t mind the 59, I have seen pretty stones with that table. I''ll keep in mind the defects you mentioned. I am considering it for a ring.
 
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!
    Lucky Alhambra Bracelet
    Lucky Alhambra Bracelet
    Handmade diamond studs
    Handmade diamond studs
    5 Diamond Misconceptions: Part 1
    5 Diamond Misconceptions: Part 1

Need Something Special?

Get a quote from multiple trusted and vetted jewelers.

Holloway Cut Advisor



Diamond Eye Candy

Click to view full-size image.

New posts

Top