GIA "brillianteering of the half-facets"????

[glitterata]

In my endless, frustrating search for a beautifully cut I1 with strong fluorescence, I''m considering this stone. GIA gives it a "very good" for cut, commenting "Cut grade is based on brillianteering of the half-facets." What on earth does that mean?

Despite the GIA Very Good cut, it gets only a 5.7 on the HCA:

Light Return: Good
Fire: Fair
Scintillation: Fair
Spread: Very Good
Total Visual Performance 5.7 - Good - Only if price is your main criterion

Here''s a snippet of the GIA report, showing the mysterious comment as well as the angles.

 

[strmrdr]

the hca is right the cut on that one sux

 

[glitterata]

I bet you''re right, Storm. I''ve pretty much eliminated it on the basis of cut.

But do you have any idea what they mean by brillianteering of the half-facets and why they think it improves the lousy cut?

 

[glitterata]

I just got a message from the vendor. If I''m interpreting it correctly, "brillianteering of the half-facets" is GIA''s term for what people around here call painting, and GIA is taking off points for it. That means they''d be giving this stone an excellent for cut if it weren''t painted--and it scores 5.7 on the HCA!

That makes no sense to me. Why would GIA love a cut that HCA hates so much?

I guess I should have paid more attention to those long, difficult, technical threads...

 

[Rhino]

DOH!

Actually it could be painting or digging. It''d be an interesting stone to see, not for purchase but for experimental reasons. Digging/painting on a stone with those proportions and well ...

 

[glitterata]

How would digging/painting affect a stone with these proportions in particular?

Maybe I should go look up some of those digging/painting threads I got lost in the first time around.

 

[Garry H (Cut Nut)]

If it was painted a little it would probably improve its appearance / reduce the table leakage.

That is the problem because GIA have used a broom grading system - they have no way to truly grade such stones.

 

[Capitol Bill]

Honestly, Garry. Do you think any degree of painting/digging could make a significant difference in this stone? Reminds me of the saying, "You can''t make a silk purse from a sow''s ear."

Bill

 

[Garry H (Cut Nut)]

Date: 5/26/2006 11:20:17 PM
Author: Capitol Bill
Honestly, Garry. Do you think any degree of painting/digging could make a significant difference in this stone? Reminds me of the saying, ''You can''t make a silk purse from a sow''s ear.''

Bill

I dont think we can make it into a silk purse (unless you used Diamond Dock to make your assessment) - but there is no doubt the stone can be improved by painting both the crown and the pavilion Bill.
The stone on the right has the proportions listed above and no painting or digging.
The stone on the right has had -6 degrees crown painting and -2 degree pavilion painting. As you can see from the ASET and DiamCalc scores it would be a better looking diamond.

I challenge GIA to devise a system to grade such a stone!!!

 

[Rhino]

Date: 5/26/2006 8:15:29 PM
Author: glitterata
How would digging/painting affect a stone with these proportions in particular?

Maybe I should go look up some of those digging/painting threads I got lost in the first time around.

Hi glitterata,

While there may be varying opinions on the subject I''ll share mine with ya and the phenomena we''re finding in both. We''re finding that once digging & painting reaches a certain threshold the diamond draws more light from the horizon than it does from above. In most circumstances light from above is strong/direct while light from the horizon is weaker, generally just reflected light off of walls, etc. and at a fraction of the intensity than you''d typically get from above. When a diamond draws more light from above it results in a brighter stone. When diamonds draw light from walls, etc., since there is generally not bright light from the horizon the facets (particularly around the upper girdle region) tend to take on a darker appearance. Of course exceptions to this rule would be during sunsets etc., then those stones light up as bright as any other.

On a critical level you can observe the phenomena in AGS ASET and what I''ve shared with you above is in accord with their teaching on the subject regarding reflected vs direct light. Green in the ASET means facets that are drawing light from the horizon (or 0-45 degree zone) which AGS says doesn''t contribute anything to helping the stone. Ie. the less of it the better. Red in the ASET indicates that light is being drawn from above (45-75 degree zone). Lots of red is good along with a nice distribution of the blues in this scope.

In diamonds that are both painted or dug you can see the increase in greens through the ASET of this phenomena. I have photography of all of this in our article on the subject and am in the process of producing a video program on the subject to help people beatter understand.

As noted in other threads, slight degrees of painting or digging will have virtually no impact on face up appearance. The one painted stone I have seen to date that did get GIA Ex I was not able to note the difference in appearance.

Hope that helps and good luck in your search glitter.

Kind regards,

 

[glitterata]

Very interesting! So in this case, GIA is giving a higher grade for brillianteering, rather than taking points off for it?

I still think I''ll pass on this stone.

 

[Rhino]

Hi Garry,

While you may prefer the painted stone on the right I think that stone would be a dawg as I think about what they actually look like in person with that degree of painting. That ASET images equates to too much green for me and I am familiar with how that would face up.

LOL... this is why folks need to see these things for themselves to make an educated judgment.

Peace out,

 

[Rhino]

Date: 5/26/2006 11:55:05 PM
Author: glitterata
Very interesting! So in this case, GIA is giving a higher grade for brillianteering, rather than taking points off for it?

I still think I''ll pass on this stone.

Actually the opposite. The stone would have gotten an EX grade glitter but for the brillianteering. The brillianteering of the girdle facets is what causes it to have a darker appearance and yes ... still pass.

This is one of those stones that we''ve been calling around here the GIA Ex steep/deeps. In a critical exam they have what I''ve coined "the ring of death". A ring of leakage that exists under the table which can be observed through reflectors like IS, Dxray, FS. Our research into this (still very young with me at this stage) is that this ring of leakage is not detectable with the human eyes until the crown/pavilion angle relationship reaches a certain threshold. To date I''ve only had one of these in my hands (a GIA Ex steep/deep) that had leakage under the table but admittedly I was not able to see this phenomena (ring of death) with my eyes and neither could the folks who we surveyed. I''m currently exploring this to a greater degree to determine when that actually becomes visible to human stereoscopic vision.

Regards,

 

[Garry H (Cut Nut)]

Date: 5/26/2006 11:56:09 PM
Author: Rhino
Hi Garry,

While you may prefer the painted stone on the right I think that stone would be a dawg as I think about what they actually look like in person with that degree of painting. That ASET images equates to too much green for me and I am familiar with how that would face up.

LOL... this is why folks need to see these things for themselves to make an educated judgment.

Peace out,

Prove it
Prove that it would be worse looking than the unpainted stone on the left with the proportions listed.

 

[RockDoc]

Suggestion for painting and digging recognition......a laser inscribed consumer oriented graphic...

On the good painted stones, maybe laser inscrbie them Rembrant, Da Vinci,Chagall etc. for the good grades of painting, for the lesser grades of painting, Picasso, Warhol and some of the abstract type artists....( forget some of the "wilder" one's names).

Then for digging..... maybe inscribe the video game character dig-dug, a mole, ground hog and maybe one of a kitty scratching in the litter box for the lowest grade.

That should make it easier for consumers.

Rockdoc