Could someone let me know the different types of flaws in diamonds, and whether one is worse than another. For example, I would assume that a fracture is worse than a feather is worse than a pinpoint.
Also, if a diamond has been filled or color-enhanced, would the GIA lab be able to detect this?
Are you asking in terms of the appearance of the inclusions (what kinds are the worst in terms of being viewed) or durability (a feather breaks girdle and compromises the stone) or both?
In terms of GIA, I do not think they grade clarity-enhanced diamonds as a policy. EGL does and notes it on the cert.
I suggest that very few people can learn enough about inclusions to make decisions as to what is better or worse.
Personally I like SI2's that have 2 -4 inclusions spread around the stone rather than 1 that is in the crown. I sometimes prefer table placement to crown, because the for the same clarity grade the crown inclusion will be larger than the table placed one.