Help me understand clarity grading.

[theMoog]

I'm wondering how accurate AGS clarity grades are. Looking at some SI1 stones the clarity map shows nothing. No red marks at all. It does state clouds and surface graining are not shown. Do these account for the inclusions and thus the SI1 rating?

And here's a VVS2 that shows a small inclusion but it's hidden under a prong. Is this surface graining on the table and not counted in clarity grading? I saw the report at the jeweler and there's nothing on the table in the clarity map of the AGS report.



And if I'm looking for eye clean SI1 stones is it better to have the inclusions be on the pavilion view and not the crown view. Does that indicate better likelihood of it being eye clean? Like this one the inclusions are shown on the pavilion view.

 

[diamondseeker2006]

You can never judge whether a stone is eyeclean or whether brilliance is affected by inclusions just by the clarity plot. That can only be determined by examining the stone. Some SI1's are eyeclean and some are not. AGS clarity grades are very accurate. Yes, clouds not shown on the clarity diagram certainly can account for an SI1 grading, and I would be cautious about a primary SI clarity grade of clouds not shown because you'd definitely need an expert to determine if the clouds are a problem. They do not attempt to draw in everything on the clarity plot. Here is some very helpful information on AGS clarity grading:

https://www.pricescope.com/journal/ags-laboratories-clarity-grading-diamonds

 

[pyramid]

I would think that is dirt on the surface on a VVS grade, you should see nothing unless at microscope magnification, not with a 10 X loupe and not being a professional at diamonds. Ask the jeweller to clean the diamond. I have read the inclusions are better hidden in SI1 diamonds if they are under crown facets and not visible through the table, but not breaking the girdle edge either.

 

[gr8leo87]

An SI clarity grade based on clouds can have adverse effects on a diamond's transparency more often than an SI clarity grade not entirely based on clouds and graining. Although SI clarity based on clouds can leave an untrained eye thinking that the stone is eye clean.

Graining: The graining doesn't affect the clarity grade if it's a transparent graining. Graining can affect clarity grade if it's white or colored.