GIA clarity clarification needed

[zhuzhu]

Hi All!

I was learning from all the valuable sources on PS and associated vendor sites, but still could not find the answer on what differentiate SI1-2/3 from I.

Some SIs are "eye-clean" and some are not. I clarity is supposed to be eye-detectable. So how to gemologist clearly and definitively differentiate the non-eye-clean SIs from Is? Is it a minimum percentage of inclusion in the table surface area that determines the class of grade?

Your input would be greatly appreciated!

Zhuzhu

 

[Tom Gelb]

Sorry but there is no set point where Si2 becomes I1.

Please note that it takes a very long time to become a good clarity grader. A clarity grader needs to see many thousands of diamonds before they can be confident in their grading. All clarity grading is done on a scale that is not perfectly objective. There are really only two objective rules for clarity grading, if there are no inclusions visible at 10X then the diamond is internally flawless, if there are no inclusions or surface features visible at 10x then the diamond is flawless. Once you move out of that range there is some subjectivity. In exact response to your question, please note that the GIA does not use the grade SI3, it goes directly from SI2 to I1.

There are five factors involved in determining a clarity:
1. Size: the size of the inclusions
2. Number: The number of inclusions
3. Location: The location of the inclusions
4. Relief: The brightness/darkness or visibility of the inclusions
5. Nature: The nature of the inclusions (this is mainly used where durability is in question).

Sorry to have not been more help.

Good luck.

 

[zhuzhu]

Date: 3/30/2010 8:21:14 PM
Author: Tom Gelb
Sorry but there is no set point where Si2 becomes I1.


Please note that it takes a very long time to become a good clarity grader. A clarity grader needs to see many thousands of diamonds before they can be confident in their grading. All clarity grading is done on a scale that is not perfectly objective. There are really only two objective rules for clarity grading, if there are no inclusions visible at 10X then the diamond is internally flawless, if there are no inclusions or surface features visible at 10x then the diamond is flawless. Once you move out of that range there is some subjectivity. In exact response to your question, please note that the GIA does not use the grade SI3, it goes directly from SI2 to I1.


There are five factors involved in determining a clarity:

1. Size: the size of the inclusions

2. Number: The number of inclusions

3. Location: The location of the inclusions

4. Relief: The brightness/darkness or visibility of the inclusions

5. Nature: The nature of the inclusions (this is mainly used where durability is in question).


Sorry to have not been more help.


Good luck.

Thank you very much! That was very helpful indeed.
Could you or someone please refer to me a article where I may find definitions on each of the 5 factors above that correspond to each classification of clarity?