difference between 1 and 2 in clarity ratings

[syjsong]

Hello,

What is the difference between the 1 and 2 in the clarity ratings, like SI1 and SI2, VVS1 and VVS2?

Is it the size, number, or position of inclusions?

 

[Garry H (Cut Nut)]

https://www.pricescope.com/tutor_clarity.asp

 

[jamesd]

Size, number and position. Any or all of those could be involved in the decision. In general, more inclusions, larger inclusions or inclusions under the table will tend to favor a lower grade.