GIA Good cut and HCA 1.5 a contradiction??

[mointampa]

Hi
Ive been reading up quite a bit on this site, but I was wondering if someone could explain something really simply.

Ive found this diamond
http://www.bluenile.co.uk/pop_int_cert_view.jsp?pid=LD01453068
Its 1.5 G VS2 Good/Ex/Ex
But gets a HCA score of 1.5 FIC

When GIA grade the stones, does it depend on the grader or is it strictly done on the proportions?

Also is it possible to say that this stone may actually be pretty good?

Hope that made sense..Thanks again.

 

[oldminer]

The GIA has not done what many of us consider their best work with their cut grading "system". You can find "GIA Good" diamonds with excellent appearances, but there is likely to be a reason, possibly of some importance, which makes the diamond not an excellent overall one to select. Of course, you can find AGS 2 or AGS 3 diamonds which also score well with HCA and have reasons why they are not AGS 0, too.

One needs to separate Light Behavior from certain elements of craftsmanship and then grade both components independently to get a meaningful and complete system. We have not yet quite arrived at who is going to be in charge since no one is totally convinced anyone has it right just yet. AGS took a rather large step back with their two-tiered approach as their excellent Platinum strategy apparently was not the overwhelming financial success it deserved to have been. Dealers want flexibility. Smart consumers want accuracy. These two ends of the commercial spectrum pull in opposing directions.

 

[Regular Guy]

Dave''s given you a whole lot of answer.

I''ll add...between GIA good, and HCA excellent, I''d prefer generally the HCA. In this case, you could consider the differential is at least partly defined by the FIC characteristic, and if you''ll read the tutorial on "what to buy," here, you''ll see that the FIC part provides a potentially unique bonus. BTW, this page has some interesting updating, with proportional conceptualizations for expense. Note, if you wish to be less racy, note the cost benefit for cut is not extremely high, relatively, and so, unless you have selected this one among others with GIA Excellent, another approach is to just find one with both Ex on GIA, and also HCA. But, you may find this one is uniquely to your liking. Consider the HCA a validation of that, and enjoy!

 

[stone-cold11]

Also, GIA tends towards the shallower crown angles while AGS in the deeper crown angle range.

 

[Garry H (Cut Nut)]

It is an intersting stone.

AGS PGS would give the stone AGS1 based on proportions

http://www.octonus.ru/oct/mss/gia&agspgs.phtml
check it here.

It is getting close to a fish eye - but has the advantage of a great spread.
It should display noticably more fire - and since no one really has a great fire measurement system, I rest my case that this should be a beautiful diamond.

 

[phoenixgirl]

Wow, that''s really neat!

My studs are both GIA very good''s with depths lower than their tables but crown and pavilion angles which still suited the less traditional percentages. Both scored 2 or under on the HCA. I was sold by the fact that they spread a bit bigger than the 0.36 carats they each are due to their depths without sacrificing cut. They are both beautiful, much more fiery than my inherited engagement stone, and they both exhibit a degree of arrows.

But without the upside of having the bigger spread, I''m not sure I would buy a 60/60 stone unless the price made up for it.

 

[raz91]

Garry, that is very neat! I'm not sure if I'm reading the chart right on your link, though ... you said the stone posted at the top (60% table, 36 degree crown, 40 degree pavilion) would be rated AGS1 based on the AGSPGS. I'm looking at the table for 60% and I see that the 36/40 combo square is G3 and in the yellow outline so AGS3/4? I'm sure I'm missing something here but wondering what it is ... mostly curious because I want see what AGS says about the diamond that I purchased (GIA Ex, 55 table, 35/41 crown/pavilion) says. Based on my reading the chart says AGS0.

 

[Garry H (Cut Nut)]

Date: 4/15/2009 8:44:35 PM
Author: raz91
Garry, that is very neat! I''m not sure if I''m reading the chart right on your link, though ... you said the stone posted at the top (60% table, 36 degree crown, 40 degree pavilion) would be rated AGS1 based on the AGSPGS. I''m looking at the table for 60% and I see that the 36/40 combo square is G3 and in the yellow outline so AGS3/4? I''m sure I''m missing something here but wondering what it is ... mostly curious because I want see what AGS says about the diamond that I purchased (GIA Ex, 55 table, 35/41 crown/pavilion) says. Based on my reading the chart says AGS0.

Sorry.
Yes you are correct Raz - I was looking at an old diff chart

 

[strmrdr]

would likely be ok in a pendant or earring but is going to have obstruction issues in a ring with a 40 degree pavilion.