Crystal spots in SI 1

[carbon lover]

I just wrote in earlier about 2 stones. This is a different topic so I thought I''d create a new thread.

The 2 stones are H SI1(GIA) and I SI1 (EGL). The H is eye clean, but under a 10x loupe there are a six black crystal spots. The I has only a couple of feathers, but looks very clean.

How could they both be SI1''s?

 

[Lugus]

For several reasons. First, they are differenet labs doing the evaluations. Second, you have humans doing the grading. They could have been tired, angry, lazy, happy, or any other number of different moods when they evaluated the stones. Third, different inclusions mean different things. They both could be SI1's only because they weren't good enough to be VS2 but there was presure not to make them SI2 (or they simply weren't SI2). My last reason is the following.
My diamond's GIA cert has a lot more marks than I'd expect on a VS1. On paper, it looks much worse than it is however. Other VS1's are worse, and others are cleaner. Sometimes you can't go by the cert though. I bet the appraisers on this forum will testify that they've found inclusions on stones that aren't even marked or noted on the cert.

 

[Mara]

Clarity grades mostly have to do with the size and location of the inclusions. A very small cloud in the table may be a VS2, but if it were a much larger cloud then it may be a SI1--again if it was even bigger it may be an I1. Or a cloud to the right of the table may be a VS1, but that same cloud in the middle of the table may be a VS2 or SI1 depending on it's size.

The black carbon spots must be pretty small if you cannot see them with your naked eye. I'm pretty good at catching black carbon in SI stones, but my earring has a small one and it's a VS and I can't see it.

I also have been told to stay away from diamonds with black carbon pinpoints in them but was never told why. Anyone care to comment?

If both stones are eye-clean to you, then that is how they got the SI grading. If they were not eye-clean..they'd have an I grading of some sort depending on the lab and grader.

 

[Giangi]

Not all SI 1s are the same... In fact SI 1 is a very broad grade... You could find a very high SI 1, almost VS 2, or a very bad SI 1, almost SI 2, with inclusions that may be slightly noticeable to the naked eye.

Giangi