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 Post subject: grading small diamonds
PostPosted: Fri Feb 23, 2018 4:46 pm 
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If you put a VS2 inclusion from a 1ct diamond into lets say a 0,1ct diamond, the 0,1ct diamond would be graded as a SI or PI, right?
Is it a good rule of thumb to grade inclusions relative to the space they occupy in a stone? For example one or two crown facets is SI grade; half the stone is PI2; etc.

Are there books that explain this or guidelines to follow for professional graders? Or do you just have to learn by comparison/experience?


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 Post subject: Re: grading small diamonds
PostPosted: Fri Feb 23, 2018 7:48 pm 
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jiznic wrote:
If you put a VS2 inclusion from a 1ct diamond into lets say a 0,1ct diamond, the 0,1ct diamond would be graded as a SI or PI, right?
Is it a good rule of thumb to grade inclusions relative to the space they occupy in a stone? For example one or two crown facets is SI grade; half the stone is PI2; etc.

Are there books that explain this or guidelines to follow for professional graders? Or do you just have to learn by comparison/experience?



Since GIA is the originator of this clarity grading system, I rely on their definitions on the grading criteria. They have courses and books that teach their grading system. You can take the course on-line, but labs must be done in person.


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 Post subject: Re: grading small diamonds
PostPosted: Fri Feb 23, 2018 9:58 pm 
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I agree with Steve. The GIA wrote the book on diamond grading...literally.
Yes clarity based on inclusions is a relative exercise.

A good overview is in this book written by Renee Newman:
Image


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 Post subject: Re: grading small diamonds
PostPosted: Sun Feb 25, 2018 9:39 am 
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thank you.

I am a bit baffled by the lack of a measurable standard for grading or finding it online. When I took a two week course at HRD antwerp they had a ruler in the microscope lens but it was only a teaching tool and only usable with the 0,5ct stones in the lab. Understandably you will have to make an educated guess at the end of the day when there are multiple inclusions in play but specifically relating to the different stone sizes I need to know if the grading is absolutely proportional to the size of the stone or whether there are various exceptions I need to know about.

Guess I need to buy some serious books.


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 Post subject: Re: grading small diamonds
PostPosted: Sun Feb 25, 2018 2:39 pm 
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Didn't HRD supply you with documentation? They should have.
Call them and ask these questions directly.
YES clarity grading is a function of the size of the stone.
Experience will increase your understanding.


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