Pol & Sym in EC cuts ?

[Ann]

when looking online, how important is Polish & Sym. in Emerald Cuts ?

And does a small or even larger culet create another plane/table ?

 

[Garry H (Cut Nut)]

in any square shaped stone achieving excellent polish and symmetry can be impossible because they often must polish a facet close to the octahedral plane and this is virtually impossible sometimes no matter how competent the cutter and better quality wheels will not solve the problem.

Culets that are big enough to see are a problem - otherwise they can protect a stone from breakage during handling etc

 

[kenny]

Garry, what about those that got a GIA Excellent for polish and symmetry?

Does GIA have low standards if it is impossible as you say?

Or did you mean very difficult?

What do you think of the GIA standard of Excellent for polish and symmetry?
Too easy?
Too hard?

I'm asking because my asscher got Excellents, and I am wondering how meaningful they are.

 

[Ann]

ok, but is a small culet on a rectangular EC too big?

 

[Garry H (Cut Nut)]

On below 2ct it would be very hard to see a culet of Slightly large

Kenny re - read plesase
in any square shaped stone achieving excellent polish and symmetry can be impossible because they often must polish a facet close to the octahedral plane and this is virtually impossible sometimes no matter how competent the cutter and better quality wheels will not solve the problem.

 

[strmrdr]

My rule of thumb is that once it hits under VG then it needs to be looked at by a skilled and trusted vendor to see if its an issue or not.
It might or might not be.
In general to avoid hassles I recomend when having stones called in stick to VG/VG but if the vendor has a stone in stock below that and is in my opinion skilled and honest enough to say its not an issue then Id consider it.

 

[strmrdr]

culet - get pictures to see how it affects it.
small is usualy fine.

depending on size larger can SOMETIMES leave a line down the center of the stone that either windows or is dark and to me looks yucky.

 

[Ann]

the line down the center, that''s what I was wondering.

If the stone is a rect. EC say, around 4cts, would even a small culet be visible?

 

[Garry H (Cut Nut)]

small is under 3% of the width - so about (8mm wide x .03 0.024mm which would be I think too hard to see.

Can you give us a real world example? I think it is unlikely a cutter would make a diamond with a visible keel

 

[strmrdr]

Date: 12/3/2006 9:39:17 PM
Author: Ann
the line down the center, that''s what I was wondering.

If the stone is a rect. EC say, around 4cts, would even a small culet be visible?

get pictures and an IS or ASET image is prefered or see it in person.
There is no way you should buy such a stone without good pictures.

 

[widget]

Ann....here''s the only picture I could find that clearly shows what the GIA called a "medium" culet on my EC. (It''s almost square, so it''s a ''short'' keel).

In real life, it''s an absolute non-issue...even with my glasses on!

Do you have pictures of the stone you''re asking about?

BTW...my stone only has G/G P&S, and it looks great...

widget

 

[Ann]

No pictures, I am studying certs, pics, and the such right now.

I have seen some EC''s where the "keel" is very apparent and I wondered
if it was supposed to be that way.

When looking at EC''s, how should the corners look? Like a mass of sparkle
or angles coming together? I know that''s hard to describe, but I''ve seen both
and I wasn''t sure what was "right" or is there a right?

I am totally ignorant on EC''s, but I think I might look. Ok, here is a stupid question,
How many step cuts should there be - make sense? Bunches of little lines or 2 or 3 ?
I guess carat size makes a difference, huh?,