Inclusions below the center

[shaiko]

Hello,

As far as I understand, in a brilliant cut diamond, inclusions below a certain height point won't have any effect of the "amount and quality" of returned light (when viewed from the top). Is this correct ? If so, will it have any effect on the clarity rating of the diamond ?

[Furqan Shafi]

Clarity grade is not based on light return. It's based on what's visible to the diamond grader under 10x magnification. So yes it may or may not have an impact on the clarity grade but that will be independent of light return. Also GIA does not grade any diamond for light return and nor does HRD or IGI (the other 2 most popular labs globally). HRD sometimes however does leave a transparency comment but that's not the light return you're talking about.

 

[davidelevi]

The answer to the second question is: if it is visible under 10x magnification through the table ("top") of the diamond, then it will be considered in the clarity grade; how "deep" (near the culet) the inclusion is, is irrelevant.

Whether it affects the grade is a different matter: the grade may be determined by another characteristic (e.g. a small cloud near the culet in a diamond that has a big feather across the crown).

The short answer to the first question is no. A big, black crystal right next to the culet will look rather horrible, and a thick cloud in the same place may make a diamond look dull.

The key here is to bear in mind that (at least in theory) inclusions graded "below" I1 (on the GIA scale) should not have any material effect on transparency and brilliance; in practice some SI2 with a lot of diffused clouds or twinning wisps may be rather hazy and dull. And some SI1 (and rare VS2) highly contrasting inclusions will not look particularly nice to the naked eye - even though transparency and brilliance will be unaffected.

Edited September 24, 2020 by davidelevi
Edited to reflect verbatim GIA wording on I1 and lower ("transparency and brilliance")

[shaiko]

Thanks.

The reason I'm asking,

I have a GIA graded diamond of IF clarity. If I look at it from the side it appears to be quite cloudy near the culet.

So if this doesn't effect how the diamond looks when observed from the top - it may not effect the clarity grade ?

[Furqan Shafi]

9 minutes ago, shaiko said:

Thanks.

The reason I'm asking,

I have a GIA graded diamond of IF clarity. If I look at it from the side it appears to be quite cloudy near the culet.

So if this doesn't effect how the diamond looks when observed from the top - it may not effect the clarity grade ?

It does affect clarity grade in my experience especially when stones are on the upper spectrum of clarity. What you are saying near the culet is unlikely to be a clarity characteristic but more along the lines of some reflection artefact. 

[davidelevi]

6 hours ago, shaiko said:

Thanks.

The reason I'm asking,

I have a GIA graded diamond of IF clarity. If I look at it from the side it appears to be quite cloudy near the culet.

So if this doesn't effect how the diamond looks when observed from the top - it may not effect the clarity grade ?

An IF-graded is unlikely to have any inclusions visible from the side whatsoever. Yes, in theory characteristics have to be visible from the top, but you may be surprised as to what is considered "visible". The diamond below was graded VVS1 because it has internal graining, not because there are any inclusions

As Furqan said, it may be a reflection of some other facet, or it may be a little bit of dirt on the outside. Can you post a photo?

[denverappraiser]

I can't imagine a correctly graded IF that has visible inclusions from the side.  Make sure it's clean. Pay attention to the surrounding environment and what might be reflecting. Make sure it's the correct stone for the report.