Surface graining?

[Jenga019]

I have two diamonds that I am comparing and both certificates say the stones have surface graining. What does that mean and how does it effect the stone?

 

[YoungPapa]

Jenga019,

It''s unimportant. It means that if you have a high powered microscope and a lot of free time you might be able to see some ridges on the surface of part of the diamond. They are not really inclusions, don''t affect value and can''t be seen by the naked eye. They have to do with variations in the grain angle of the stone.

Most of the comments listed on a GIA report (surface graining, additional clouds not shown, etc) are really just there so GIA can say "Hey - we documented everything - even the unimportant stuff that only a gemologist might care about". The only comments that''s are going to be negative involves crown angles or laser drilling and those are both very rare.

 

[Garry H (Cut Nut)]

it is an identifying feature - handy if you ever need to prove to the police the diamond is yours - and as YPappa says - then if the stone is resubmitted the lab can match it up - and give it the same grade and get paid again

If grain lines are really bad the 'polish' will be poor or fair.

 

[snlee]

My GIA cert says that as well. It also says " pinpoints are not shown." I know it''s unimportant but I was wondering...what are pinpoints?

 

[mdx]

Graining lines are often a result of twinning or a growth defect in the crystal structure. They look a bit like polishing lines but can be identified by the fact that they cross facet junctions. Polishing line can’t do that.
Nothing to worry about, just an interesting identification feature.

Pinpoints are small rounded, usually white inclusions that are visible under 10x magnification but not large enough to be distinguishable as an included crystal.
They are sometimes included in a plot (see sample plot) but often just mentioned in comments.

Johan