GIA very good vs excellent cuts

[ucbryan]

I just started looking around for a stone and wanted to know how important is an "excellent" rating for cut vs a "very good" cut on a GIA cert. In theory is a well cut excellent going to outshine a well cut very good? A stone I have info on has these numbers

1.4c/G/S1 very good cut
pavillion angle 41, crown angle 32.5; plugged it into the HCA and got .7
table is 56, depth is 60.8
i have the idealscope and aset too..but i dont know how to read the difference between a very good to excellent on the charts.

Can you guys also help see if you can find any stones you think are worthy. price around $9500 hoping to get the best cut round brilliant diamond as near 1.5c as possible.

 

[Lorelei]

Date: 1/29/2009 5:23:58 PM
Author:ucbryan
I just started looking around for a stone and wanted to know how important is an 'excellent' rating for cut vs a 'very good' cut on a GIA cert. In theory is a well cut excellent going to outshine a well cut very good? A stone I have info on has these numbers

1.4c/G/S1 very good cut
pavillion angle 41, crown angle 32.5; plugged it into the HCA and got .7
table is 56, depth is 60.8
i have the idealscope and aset too..but i dont know how to read the difference between a very good to excellent on the charts.

Can you guys also help see if you can find any stones you think are worthy. price around $9500 hoping to get the best cut round brilliant diamond as near 1.5c as possible.

Welcome,

Firstly evaluate each diamond on its own physical proportions initially, these cut grades can be wide and encompass some less desirable cut combos, so thats the first approach. The aim with the HCA is to score < 2 then such diamonds are considered a ' pass pending further evaluation' which is done with Idealscope images and ASET. If you prefer to shop in person, then you could try this tactic as our Ira suggested once, see if you can run the proportions of the diamonds you like through the HCA if there is a computer available, and look at them through your IS and ASET to evaluate further. Also check such diamonds out away from the store lights to get a better idea of how they look in everyday lighting.

The diamond above scoring .7 is worth a further look, do you have the girdle thickness for this diamond, polish, symmetry and diameter? Also with the ASET and IS it is reasonably straightforward to interpret the results so don't be worried that you will go wrong as you won't with all the ammunition you have to hand!

 

[stone-cold11]

Date: 1/29/2009 5:23:58 PM
Author:ucbryan
I just started looking around for a stone and wanted to know how important is an ''excellent'' rating for cut vs a ''very good'' cut on a GIA cert. In theory is a well cut excellent going to outshine a well cut very good? A stone I have info on has these numbers

1.4c/G/S1 very good cut

pavillion angle 41, crown angle 32.5; plugged it into the HCA and got .7
table is 56, depth is 60.8
i have the idealscope and aset too..but i dont know how to read the difference between a very good to excellent on the charts.
Can you guys also help see if you can find any stones you think are worthy. price around $9500 hoping to get the best cut round brilliant diamond as near 1.5c as possible.

Looks good. This stone is near the Brilliant Ideal Cut parameters, so it will probably look more brilliant but less firey. Can you upload the IS, ASET? We will take a look.

 

[ucbryan]

thanks for the info. im going this remotely so i guess im trying to arm myself w/ the most information possible. the polish is EX, the symm is VG, girdle is thin to med faceted. is diameter the measurement? 7.24-7.33 x4.43.

Also i just noticed the cut was affected by brillianteering. What is that? Thanks.

 

[John P]

Date: 1/29/2009 5:53:13 PM
Author: ucbryan
thanks for the info. im going this remotely so i guess im trying to arm myself w/ the most information possible. the polish is EX, the symm is VG, girdle is thin to med faceted. is diameter the measurement? 7.24-7.33 x4.43.

Also i just noticed the cut was affected by brillianteering. What is that? Thanks.

Given the other specifics that comment is the reason for the VG grade. It means the diamond''s upper or lower girdle facets were not normally indexed.

Short answer: If the variation is slight it may not be a big deal, but if the diamond was dug or the pavilion was tinkered-with it could imply undesired darkness. If you can post an AGS ASET or Ideal-Scope image there are several pros here who can interpret what was done and to what degree.

Technical answer:
http://www.diamondcut.gia.edu/pdf/6_05_RDR_pg239_243pdf.pdf

Case studies specific to near-Tolk makes (yours is close-ish):
http://journal.pricescope.com/Articles/45/1/Visible-Effects-of-Painting--Digging-on-Superideal-Diamonds.aspx

 

[ucbryan]

im attempting to load these up from a mac.....will continue trying.

 

[stone-cold11]

Date: 1/29/2009 5:53:13 PM
Author: ucbryan
Also i just noticed the cut was affected by brillianteering. What is that? Thanks.

OIC, this is what is affecting the cut grade. I can''t explain them very well too, but GIA will reduce a cut grade due to excessive brillianteering.

Hope John can see this and explained it to you.

 

[Rhino]

It may actually be both too. Brillianteering and also the proportion combo. It would be interesting to see whatever data you can muster on it.

 

[ucbryan]

well i cant load the photos so here is the link to the actual webpage.

http://www.exceldiamonds.com/Loose_Round_Diamond-143/Loose_Round_1.42_Carat_G_Color_SI1_Clarity_diamond-278576.html#

on another topic, if i was going to set this in a cusion halo setting, would the size of the center stone..say from 1.3-1.5 carats be a noticeable difference?

 

[stone-cold11]

Looks like visible brillianteering to me in the 10X pic. Not sure how it will affect visual in real life.

 

[John P]

Rhino, with lower halves at about 80% the proportions get GIA EX (edited to add; confirmed - stars 50 lh 80).

Bryan, the cut grade is due to some crown-only painting. Judging by the ASET image it's right at the 4-degree threshold GIA enforces for all diamonds. In the case of steep pavilions this is not the issue it is with shallow makes.

The images look good. With this dealer you can get a visual assessment to verify that: Get Judah or Barry on the phone and ask about the brillianteering directly; specifically is there any darkness at the girdle in any lighting? The ASET looks good on the whole. The green at the 10:00 position is either an artifact of the photo setup or the indented natural - at normal size it's likely to be a non-factor.

 

[Lorelei]

Date: 1/29/2009 6:29:47 PM
Author: Stone-cold11

Date: 1/29/2009 5:53:13 PM
Author: ucbryan
Also i just noticed the cut was affected by brillianteering. What is that? Thanks.

OIC, this is what is affecting the cut grade. I can't explain them very well too, but GIA will reduce a cut grade due to excessive brillianteering.

Hope John can see this and explained it to you.

GIA can lower cut grades for brillianteering and it will say so in the comments section of the grading report if that is the case such as " cut grade affected by brillianteering". Whether any such treatment is detrimental to the desirable physical properties of that particular diamond requires idealscope and preferably expert evaluation.

 

[strmrdr]

Not my favorite combo...
crown angle 32.5 already has little upper girdle definition then add a lot of painting on 1/2 the diamond to further blend them together.
I'm not a fan of the diamond at all.
Looking around the price is high also.
Personally I would get a better cut.

 

[strmrdr]

personally I would have Mark or another vendor see if this AGS0 is eyeclean...
http://www.engagementringsdirect.com/loose_detail.php/session/c2b29f08422bff8649af95b0bd55a926/id/19273365/sz/150/premium/premium

 

[ucbryan]

what about the cut combination (w/ the brillianteering) do to the stone in terms of appearence and light performance? I had barry and judah take a look at this stone and they said its light performanc is great. Any insight would help. Thanks

 

[stone-cold11]

Date: 2/3/2009 2:59:38 PM
Author: ucbryan
what about the cut combination (w/ the brillianteering) do to the stone in terms of appearence and light performance? I had barry and judah take a look at this stone and they said its light performanc is great. Any insight would help. Thanks

Read this link,
http://journal.pricescope.com/Articles/45/1/Visible-Effects-of-Painting--Digging-on-Superideal-Diamonds.aspx, if you really want to have your own opinion rather than trust your vendors opinion.

 

[Lorelei]

Date: 2/3/2009 2:59:38 PM
Author: ucbryan
what about the cut combination (w/ the brillianteering) do to the stone in terms of appearence and light performance? I had barry and judah take a look at this stone and they said its light performanc is great. Any insight would help. Thanks

Brillianteering is a controversial topic here, some don't like it and others are open to it if it enhances the desirable visual properties of the diamond. I am no expert but the diamond you posted looks good to me.

Here is a thread you might find helpful.

https://www.pricescope.com/community/threads/girdle-treatments-cheated-girdles-tweaked-girdles-digging-painting.36102/