Inclusions

[bgray]

Is a feather really a crack? What is a twinning wisp? What is the most egregious value lowering inclusion?

 

[Lorelei]

Date: 3/19/2010 10:00:14 PM
Author:bgray
Is a feather really a crack? What is a twinning wisp? What is the most egregious value lowering inclusion?

Hi B!

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Twinning Wisps....Below is a quote from John Pollard and there are lots of threads in the archives,

"Twinning wisps result from crystal distortion during growth. They're flat or ribbon-like cloudy areas, often radiating out from the diamond's center. Surface Graining is diamond structural irregularity which you could see with a microscope. Neither hurts the diamond's value and a GIA VS2 is a very safe grade, even if it has a more significant inclusion - such as a feather.

Many times a diamond grading report will list things as 'not shown.' The diamond's report is just noting that these things exist for sake of thoroughness. The characteristics which are 'not shown' are non-issues.

As an aside - though we call diamonds without visible inclusions 'flawless' we don't usually call clarity characteristics 'defects' (in the trade anyway). Mother nature was responsible and some people consider inclusions and blemishes natural 'fingerprints' which make their diamond special."

Useful thread showing twinning wisps.

http://www.goodoldgold.com/4Cs/Clarity/InclusionGallery/

As to the last question, it very much depends I believe on the diamond and its particular inclusions but one of the experts might have some actual data on this.

 

[bgray]

Thank you Lorelei!

Lorelei: the patron saint of Prosumers.

 

[Lorelei]

Date: 3/20/2010 9:35:13 AM
Author: bgray
Thank you Lorelei!

Lorelei: the patron saint of Prosumers.

 

[Collee]

Date: 3/20/2010 9:35:13 AM
Author: bgray
Thank you Lorelei!

Lorelei: the patron saint of Prosumers.

as well as poise and patience.

 

[Lorelei]

Date: 3/20/2010 10:28:37 AM
Author: Collee

Date: 3/20/2010 9:35:13 AM
Author: bgray
Thank you Lorelei!

Lorelei: the patron saint of Prosumers.

as well as poise and patience.

Thats also a lovely compliment Collee, thank you!!!

 

[Tom Gelb]

I am unsure if this answers your secnd question or not, but I believe that the most egregious or value lowering inclusion is a cleavage. A cleavage is a large feather or crack that runs along a growth plane (cleavage plane) of the diamond. Most diamonds grown in layers and are weakest along those layers, or growth planes. A feather along one of these cleavages is most susceptible to getting bigger if some blow or temperature change occurs. Diamonds with cleavages sometime break all the way through. One of the criteria of clarity grading is the nature of an inclusion, and the nature of a cleavage is that the stone may break in two. Thus these are generally given imperfect clarity grades (I1-3). I hope this helps.

Good luck.

 

[diagem]

Date: 3/20/2010 6:59:11 AM
Author: Lorelei

Date: 3/19/2010 10:00:14 PM
Author:bgray
Is a feather really a crack? What is a twinning wisp? What is the most egregious value lowering inclusion?

Hi B!

[/url]

Twinning Wisps....Below is a quote from John Pollard and there are lots of threads in the archives,

''Twinning wisps result from crystal distortion during growth. They''re flat or ribbon-like cloudy areas, often radiating out from the diamond''s center. Surface Graining is diamond structural irregularity which you could see with a microscope. Neither hurts the diamond''s value and a GIA VS2 is a very safe grade, even if it has a more significant inclusion - such as a feather.

Many times a diamond grading report will list things as ''not shown.'' The diamond''s report is just noting that these things exist for sake of thoroughness. The characteristics which are ''not shown'' are non-issues.

As an aside - though we call diamonds without visible inclusions ''flawless'' we don''t usually call clarity characteristics ''defects'' (in the trade anyway). Mother nature was responsible and some people consider inclusions and blemishes natural ''fingerprints'' which make their diamond special.''

Useful thread showing twinning wisps.

http://www.goodoldgold.com/4Cs/Clarity/InclusionGallery/

As to the last question, it very much depends I believe on the diamond and its particular inclusions but one of the experts might have some actual data on this.

So very true...
More-so, it depends on the Diamond''s faceting design & angles as any internal inclusions are particles that will somehow interfere with the free-flow of light traveling through the cut itself.

For example..., an SI/I type crystal inclusion might be masked nicely by a brilliant cut design but could be easily visible in a step-cut design.
Contrarily, the same inclusion might be wrongly positioned in a brilliant cut resulting in multiple reflections (some might even look dark) easily viewed/noticeable and might appear aesthetically fine in a step cut design.

Basically..., it will depend on a stone per stone basis.

Some inclusions are actualy interesting and welcomed characters created by mother nature & enhanced by the cutter.

 

[Dreamer_D]

Related question (hope you don't mind BGray): Are twinning whisps similar to clouds in the sense that too many of them can affect optical performance?

 

[Tom Gelb]

Yes, they are very similar and can block light as it moves through a diamond.

Good luck.

 

[Lorelei]

Thanks so much for the excellent information Tom and DiaGem!

 

[Dreamer_D]

Thanks!

 

[diagem]

Date: 3/20/2010 11:11:14 AM
Author: Tom Gelb
I am unsure if this answers your secnd question or not, but I believe that the most egregious or value lowering inclusion is a cleavage. A cleavage is a large feather or crack that runs along a growth plane (cleavage plane) of the diamond. Most diamonds grown in layers and are weakest along those layers, or growth planes. A feather along one of these cleavages is most susceptible to getting bigger if some blow or temperature change occurs. Diamonds with cleavages sometime break all the way through. One of the criteria of clarity grading is the nature of an inclusion, and the nature of a cleavage is that the stone may break in two. Thus these are generally given imperfect clarity grades (I1-3). I hope this helps.

Good luck.

Hi Tom...

I believe you are talking about an extreme situation here..., the chances a Diamond will break in two in a partial cleavage plane (most are partial) is extremely rare and should not worry consumers. (unless the cleavage plane is cracked from one end to the other end of the Diamond and even then I wouldnt worry too much).
If these cleavages survive the numerous cutting stages they will probably survive day to day wear.

I have seen plenty of feathers earning VS-SI grades which were actually hard to view with the unaided eyes and sometimes even with our loupes.

 

[diagem]

Date: 3/20/2010 11:38:31 AM
Author: dreamer_d
Related question (hope you don't mind BGray): Are twinning whisps similar to clouds in the sense that too many of them can affect optical performance?

Wisps can be extremely tricky inclusions and the have the ability to appear colorless in one position and dark in another.
Twinning wisps must be checked in as many lighting environments as possible.

ETA: The fashion a Diamond with twinning wisps is set will also determined how the wisps will appear. Some bezel settings will obstruct light making the wisps appear dark (just like the arrows on a RB but might stay dark permanently

.)

 

[Tom Gelb]

Sorry, I may not have been clear. A cleavage is an unusual inclusion, at least in diamonds I have seen/graded. I am speaking specifically about the types of inclusions described as cleavages in grading reports. That being said, yes even in these cases it is unlikely that the diamond will break, but it is possible, which leads to the very low clarity grades associated with this type of inclusion. Sorry to have been unclear previously.

Good luck.