- Aug 8, 2005
I could respond. But it would not be concise. Please help with questions below.
SparklySoprano|1423422356|3829393 said:First, the term "feather" means a fissure within a diamond. This "fissure" can actually be called other things. So, it's still in essence a "feather," but it depends upon where how it is included as to what it is actually called. But for the sake of clarity, I will use the term "fissure" in my humble definitions below, which are based upon GIA grading "rules."
Feather = a fissure that is close to the surface of the diamond without breaking the surface
Cavity = a fissure that breaks the surface by creating an opening
Included crystal = a fissure that is included but not at the surface
Needle = a fissure that is actually straight (a 'straight feather' is how I've seen it described, so does this mean it could be defined as not having broken the surface?)
Most feathers were created when the diamond was formed or when it was pushed to the earth's surface. The formation likely happened billions of years ago.
The size and position of the fissure is important when considering the diamond. Three main questions to ask are:
1) Does it create an opening on the surface? (My follow up question to this: 'Wouldn't this inclusion actually be called a cavity in a GIA report?')
2) Does it reach the girdle edge? (Having surmised from the readings that extremely or very thin girdles would be most at risk, I would ask: what if the girdle is medium to slightly thick? Would that be a better scenario?)
3) Does it make a connection to other feathers near the surface? (I'm theorizing that this would not be good because more than one together at some point just compounds the potential negative impact.)
After surviving the cutting process, it is unlikely that a feather will worsen. Some experts in the main report I read were more concerned than others. What I surmised is that generally, if one can satisfactorily answer the three questions posed above, that should create considerably less worry about the situation. Of course, the lower in clarity grade, the more concern one could have. Some felt that SI2 is where that doubt really seeps in, whereas, some felt even lower, e.g. I2.
I also learned regarding cleavage planes that if a feather is located on one, "it can extend as a result of impact, but this is rarely seen in fully faceted diamonds. If it's going to split as a result of cleavage, it will split during cutting. Cleavage is an uncommon clarity." (Quote possibly somewhat paraphrased from PS report; I'm using my notes.)
I'm still feeling a little confused about cleavage and cleavage points, in particular how one can see them. Is it only upon viewing the magnified diamond itself? I read that diamonds have perfect cleavage in 4 directions. The cleavage plane is an internal direction of weakness. Cleavage also has something to do with the cutting process, although I believe in older methods. Cutters would sometimes use cleavage to divide the rough before faceting.
So, going back to my earlier post's questions:SparklySoprano said:Gypsy, for learning purposes, could you please be more specific about "breaking the surface?" Also, would this concern also have something to do with not wanting the feather to interfere with cleavage points? Thanks!
I would now say that "breaking the surface" means that the inclusion is actually a cavity (or should be listed as one on the GIA report). A "feather" should be one that is close to the surface without breaking it. And "breaking the surface" from what I saw on various picture examples, makes the diamond look chipped in my humble opinion.
And the concern about the feather interfering with the cleavage points would be a more unlikely scenario since the diamond would likely have split during the cutting process. However, the feather could extend as a result of impact in this case, but is rare in fully faceted diamonds.