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?
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.
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.
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21600 Location: San Francisco
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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