In a SI1 diamond, what type of inclusion is the worst?

[mcblohe]

I see in GIA reports that there are inclusions such as crystal, feather, cloud, thinning wisp... What exactly are thinning wisp and which inclusion is the worst to have?
Thanks

 

[MissGotRocks]

In my opinion, the worst inclusion to have in an SI stone is one major one. Several pinpoints or small inclusions spread out throughout the stone will give you a better chance of being eyeclean but it would be the number of them that would give you an SI grade.

Twinning wisps are nothing more than crystals together that form a type of 'line' if you will - they can be great inclusions as they are often not seen with the naked eye. That's not always the case either though.

Each stone has to be reviewed on a case by case basis though - some on plots would seem to be almost invisible to the naked eye but in real life they are visible. Working with a good vendor who will give you an honest assessment of the inclusions and whether or not they feel the stone is eyeclean is best - particularly when they have the stone in hand to assess.

 

[diamondseeker2006]

The worst is one you can see with your eyes from the top or the sides. Placement is everything.

 

[slg47]

in my opinion, the worst would be an eye-visible one. SI stones will have inclusions (they are graded SI for a reason) so check with vendor about if they are eye-visible or not, and whether or not there are any durability concerns (not likely but good to check)