Girdle Question

[kenny]

I read John Q''s thread about this painted and dug in girdles:

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

I''m confused.
Why does the direction of polishing matter?
Is diamond like wood, with grain?
If so, since a round diamond is round they have to polish facets over the full 360 degrees.
So wouldn''t it be a wash?


And why would direction of polish result in different crown angles anyway?
You could polish away more or less regardless of direction of polish or grain.
And couldn''t they polish any facet to any angle?

 

[Carlotta]

Have been searching, also.........

Did you see this article????

www.diamondcut.gia.edu/pd/6_05_RDR_pg239_243pdf.pdf

 

[Carlotta]

looks like the link didn''t work.....maybe you can find it ..........

 

[Carlotta]

try again

www.diamondcut.gia.edu/pdf/6_05_RDR_pg239_243pdf.pdf

 

[Lynn B]

Good question, Kenny, I am unclear on this still - and I just re-read JohnQ''s thread, too! (In fact, I posted this very question over on Rhino''s GIA thread - but this is probably the better place to ask.)

Is there any way to tell if my AGS-0 stone has a painted girdle?

Thanks,
Lynn

 

[Carlotta]

Lynn, can you get the link to work???? (newbie here.........)!!!
Thanks..........

 

[JohnQuixote]

Date: 3/13/2006 10:31:18 AM
Author:kenny
I read John Q''s thread about this painted and dug in girdles:

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

I''m confused.
Why does the direction of polishing matter?
Is diamond like wood, with grain?
If so, since a round diamond is round they have to polish facets over the full 360 degrees.
So wouldn''t it be a wash?


And why would direction of polish result in different crown angles anyway?
You could polish away more or less regardless of direction of polish or grain.
And couldn''t they polish any facet to any angle?

Kenny,

Graining in diamonds is very complex. Diamonds will only run on the wheel in certain directions. One facet may run in one direction, another may run only in another direction. Each facet is ''taken'' (run on the wheel) from a planned starting point to a planned finishing point. In a general sense, upper and lower girdle facet polishing is done from girdle outward or from the poles inward as indicated in the photos.

Unlike wood polishing, the facet face must be polished in one specific direction and it must be flat unto itself.

The polishing wheel is impregnated with diamond dust. Any contact removes material from the diamond being polished. Even if you run it for a moment, the starting point of contact will have more material removed than the finishing point of contact. This means if you choose to begin at the girdle and polish towards the crown or pavilion (traditional brillianteering and ''digging'') there will be more material polished away from the girdle area than the finishing point. If you choose to begin at the star, or on the pavilion, and finish at the girdle (painting) there will be more material polished away from the starting point than from the girdle.

In general, most diamonds are traditionally finished. If the girdle is quite thick it may be more aggressively polished starting at the girdle, or ''dug'' in order to reduce the girdle''s thickness. A with a medium or thin girdle at the time of brillianteering may be painted to preserve the girdle and, in the case of optically symmetrical diamonds, to acquire the no light-leakage, broadfire effect.

 

[JohnQuixote]

Date: 3/13/2006 10:56:56 AM
Author: Lynn B

Is there any way to tell if my AGS-0 stone has a painted girdle?

Ideal-scope images below: Traditional brillianteering (left), painting (right).

Capable cutters would point out that the minimal-leakage footprint on the right is not a definite sign of painting: There are other ways of running a stone that will acquire such a look in a reflector.

My observations below are specific to diamonds with good optical symmetry, which behave differently than those without. Others can comment on painted or dug diamonds cut purely for weight retention, not optical symmetry (we don't see many of those on PS).

When there is spread in the angular relationships (associated with traditional brillianteering), light returning to the viewer’s eye is splintered along symmetrical paths and junctions at different angles, giving an intense, on-off look to the scintillation. In diamonds with balanced major and minor configurations the sharper dispersion is beautiful in all illumination scenarios, with small pinpoint flashes that are especially intense in bright light conditions.

When the angular relationships of the facets are closer (associated with painting), light return flows easily across the closely matched angles. In diamonds with balanced major and minor configurations this creates large, broadfire scintillation, described as fluid and colorful. The spectral colors are especially notable in soft light conditions like candlelight, when your pupils are dilated.

 

[Small]

Thanks for posting this...I was having a hard time understanding all of that as well. With John''s IS pictures and explanation I understand a bit better

 

[oldminer]

It sure sounds as if either painting or digging can be useful in getting a sought after overall end result. These are expert terms that are nothing new, but people seem to feel a little frightened when they hear the terminology. Nearly every diamond has a decision maing process behind its cutting. The end result is what the consumer gets to appreciate. When done properly, there is no problem with an appropriate amount of painting or digging. When the diamond is finished, it speaks for itself.

 

[Carlotta]

Date: 3/13/2006 1:56:29 PM
Author: oldminer
It sure sounds as if either painting or digging can be useful in getting a sought after overall end result. These are expert terms that are nothing new, but people seem to feel a little frightened when they hear the terminology. Nearly every diamond has a decision maing process behind its cutting. The end result is what the consumer gets to appreciate. When done properly, there is no problem with an appropriate amount of painting or digging. When the diamond is finished, it speaks for itself.

But re: the above GIA article - how can the consumer know when it is enough/vs too much???

And why isn''t this disclosed/represened on the AGS cert??? The consurmer should be able to make an INFORMED choice.....

 

[JohnQuixote]

Date: 3/13/2006 2:02:16 PM
Author: Carlotta

But re: the above GIA article - how can the consumer know when it is enough/vs too much???

And why isn't this disclosed/represened on the AGS cert??? The consurmer should be able to make an INFORMED choice.....

Carlotta, these are differences in microns, with no agreed definitions. One group might say 'this diamond is digged' where another would disagree.

The practical approach suggests it's 'too much' if the effects on performance are deleterious.

AGS accounts for this in their light performance metric. Every diamond is measured, so a diamond with great optics, where brillianteering is additive, will still acquire a 0 in the light performance grade. If the brillianteering (whether traditional, dug or painted) was deleterious it will not.

GIA has decided to profile all diamonds with non-traditional brillianteering as deleterious, even if the brillianteering was additive. This protects consumers against average situations where the intent was to retain weight at the expense of beauty. Unfortunately it also stereotypes some carefully crafted premium diamonds as behaving a certain way when they do not.

 

[JohnQuixote]

Date: 3/13/2006 1:56:29 PM
Author: oldminer
It sure sounds as if either painting or digging can be useful in getting a sought after overall end result. These are expert terms that are nothing new, but people seem to feel a little frightened when they hear the terminology. Nearly every diamond has a decision maing process behind its cutting. The end result is what the consumer gets to appreciate. When done properly, there is no problem with an appropriate amount of painting or digging. When the diamond is finished, it speaks for itself.

Well-said.

 

[Lynn B]

Thanks, John. Appreciate the detailed information.

Feeling a bit ashamed to admit this

but still wondering... is this, then, (likely) a painted girdle?

(It''s the IS of my stone. 2.36 AGS-0, 55, 60.5, 34.4, 40.

Thanks!

Lynn

 

[JohnQuixote]

Date: 3/13/2006 3:27:11 PM
Author: Lynn B

Thanks, John. Appreciate the detailed information.

Feeling a bit ashamed to admit this

but still wondering... is this, then, (likely) a painted girdle?

(It's the IS of my stone. 2.36 AGS-0, 55, 60.5, 34.4, 40.

Be not ashamed. Asking questions is good.

I can't say 100% without more; remember, 34.3 and 40.8 are each averages of 8 different numbers - they reveal nothing of the 16 upper girdle angles, 8 star facet angles & % on the crown, and 16 lower girdle angles on the pavilion (stars look to be 50-55%). Having made the disclaimer...

Yes - most crown facet junctions in your ideal-scope image are consistent with painting.

Author: Oldminer

Nearly every diamond has a decision maing process behind its cutting. The end result is what the consumer gets to appreciate. When done properly, there is no problem with an appropriate amount of painting or digging. When the diamond is finished, it speaks for itself.

How does your diamond speak, Lynn?

 

[Lynn B]

Date: 3/13/2006 9:38:28 PM
Author: JohnQuixote

Date: 3/13/2006 3:27:11 PM

...How does your diamond speak, Lynn?

It speaks quite well, thank you!

It says charming and modest things like, "Aren't I pretty?", "Aren't I sparkly?!", and "You love me, don't you?"

Lynn

PS Thanks for the info, John. That's what I *thought*!

PPS ETA: Has the dang "QUOTE" feature changed lately? I am having a HECKUVA time with it these days!!!

 

[Lynn B]

And John, TOTALLY off-topic, but how in the world do you quote two different "authors" (me and Dave) in ONE post, like you did above? Apparently I am either Quote-Challenged or living in Quote Purgatory because I am having a terrible time!!!!

Thanks!
Lynn

 

[jasontb]

Date: 3/13/2006 9:55:01 PM
Author: Sample Quote 1
I made this message up , it''s not real

Date: 3/13/2006 9:55:01 PM
Author: Sample Quote 2
Another sample. You can make all the quotes you want by just using the html tags for quotes in your message.

To start a quote, type the word QUOTE inside square brackets []. To end a quote, type /QUOTE inside square brackets [].

If you want to add the bold date and author lines to you quote, use the tags in the brackets as before. Now make the first two lines of the quote:

Date:[/b] 3/13/2006 9:55:01 PM
Author:[/b] Sample Quote 2

but don''t put the *''s in fron of the b''s

Favorite Color: Blue
Hair Color: Brown
Maybe John used some simpler method that I don''t know about. But I think he did it by copying and pasting text and html as I descibed above.

 

[Lynn B]

Jason,

Thanks so much for the Quote 101 Lesson! I appreciate it!

So you don''t use the "QUOTE" button at all, then?

Lynn

 

[Sunshines]

Hi guys, sorry, still dont quite understand the painting and dugging techniques, some quick questions.... can GIA Ex cut and AGS O Ideal (supposedly the top stuff) be potentially painted or dug? will the price of stone be affected as a result of the techniques?

 

[JohnQuixote]

Date: 3/13/2006 9:55:01 PM
Author: Lynn B
And John, TOTALLY off-topic, but how in the world do you quote two different 'authors' (me and Dave) in ONE post, like you did above? Apparently I am either Quote-Challenged or living in Quote Purgatory because I am having a terrible time!!!!

Thanks!
Lynn

LOL Lynn. I do a lazier version of the Jason method. I go to the first post I want to quote, hit reply, select HTML at the bottom, then hit quote. The quote is imported in HTML format. I copy it, hit cancel, go to the second post, hit reply, select html, hit quote and import that quote in HTML. I paste the first text (HTML of the first quote) above or below, put in a
and select Normal at the bottom. It all reverts to normal view, with both quotes, and I can do as I wish.

 

[jasontb]

Date: 3/14/2006 6:16:58 AM
Author: Lynn B
Jason,


Thanks so much for the Quote 101 Lesson! I appreciate it!

So you don''t use the ''QUOTE'' button at all, then?


Lynn

As John said, I think the easiest thing to do is use the quote button to have the forum software generate everything automatically. But then you can edit/copy/paste it as html to your heart''s content.

 

[Lynn B]

Thanks, guys! YOUS IS DA BEST!

 

[JohnQuixote]

Date: 3/13/2006 1:56:29 PM
Author: oldminer
It sure sounds as if either painting or digging can be useful in getting a sought after overall end result. These are expert terms that are nothing new, but people seem to feel a little frightened when they hear the terminology. Nearly every diamond has a decision maing process behind its cutting. The end result is what the consumer gets to appreciate. When done properly, there is no problem with an appropriate amount of painting or digging. When the diamond is finished, it speaks for itself.

I'm seeing this as well.

These approaches have been around for generations. Digging and painting are just words. They are parts of the manufacturing process, like cleaving, sawing, blocking, etc. They are not common parlance when discussing diamonds in the mainstream: If you drop these terms there are many jewelers and appraisers who won’t even know what you’re talking about. They are nothing to fear. Poor brillianteering will result in an inconsistent, wavy or knife-edge girdle, which will be downgraded by reputable labs.

A lot of buzz (and worry) has been created on the forum lately. Here is a simple overview.

With the vast majority of diamonds:

The thickness of the girdle is marked at blocking, and revisited before brillianteering. As the polisher puts the facets on he meets those marks. He may dig a bit or he may paint, depending on the desired yield and girdle thickness. It is all very natural. The approach is like choosing a fork or a spoon, according to the dessert you’re eating. The intent is to finish the diamond beautifully, particularly in premium makes (often seen on PS) where utmost care is taken throughout the process.

In extreme cases:

The main reason for extreme digging is because a stone may be steep/deep and there is a need to make that stone appear to have a medium or thin girdle. Remember, the desired girdle thickness is marked. By digging the upper and lower halves, starting from the girdle out toward the poles, thinning of the girdle occurs and the cutter meets the mark. This tends to hide weight. Digging may also be referred to as gouging.

In the case of shallow diamonds (where the girdle is marked to be quite thin), the cutter may need to start from the poles and polish toward the girdle to preserve the marks and avoid thinning the girdle any more. This is painting. If too much material is taken away it could result in a knife-edge girdle.

Of the two, digging is far more deleterious than painting. It can hide weight and reduce performance.

The ‘buzz’ lately is because GIA has decided to downgrade a certain level of digging or painting without analyzing the actual diamond. This is positive for average consumers in common situations (like the mall) as they will be protected from gouging for the purpose of saving weight… Unfortunately, a small baby was thrown out with their bath water: A few brands of the most carefully finished premium diamonds are painted on purpose. Coupled with optical symmetry, this technique can result in some of the most spectacular diamonds in the world. Unfortunately, along with such shortcuts as rounding of numbers, GIA is lumping that tiny percentage of wonderful premium makes in with the larger percentage of ‘save the weight’ cases.

With premium optical symmetry, like we often see on Pricescope, beauty was always the objective. It was not about saving weight. If the girdle is consistent and the painting was deliberately designed to beautify (as with Lynn’s diamond) it should not be downgraded.

Hope this helps.