knot

[aggiefan]

What is "knot" on a GIA certificate diagram?

 

[Rank Amateur]

One kind of a knot is an inclusion that is really a tiny diamond. I think of them like a knot in a tree - it's all tree, but the knot refuses to grow with the grain.

www.gia.org has an online dictionary which talks a little about knots.

R/A

 

[dimonbob]

Welcome to the forum AggieFan,

Are you from Texas?

A knot in a diamond is a hard spot on the surface caused by twinning. Knots give the diamond cutter and polisher fits because they almost always leave drag lines from them and the knot itself may end up as a rough spot without that nice polish.

 

[aggiefan]

Thank you for your answers. Yes, I am a Fightin' Texas Aggie!

So, another question...is that a particularly BAD type of inclusion? Should I avoid a stone with this? Can you see it with the naked eye in an SI1?

 

[dimonbob]

Hi Aggie,

The only problem that knot has is when the unlucky cutter and polisher had to deal with it. Otherwise, it should not give you any problam at all as long as you cannot see it without a loupe.
Enjoy!

 

[niceice]

According to the GIA a "knot" is "an included diamond crystal that extends to the surface of the diamond after fashioning"... A "twinning wisp" is a "series of pinpoints, clouds, or crystals that forms in a diamond's growth plane; associated with crystal distortion and twinning planes"... We just rejected a diamond that had a knot in it, but took the opportunity to add the picture to our inclusion library, here it is:

This is a close-up of the knot:

And for those who may be wondering, the plotting diagram for it looks like this with the knot indicated by the red arrow:

And the answer to Leonid's question is "we served the pics off of our server"

 

[dimonbob]

GIA is not the last word nor the only authority when it comes to all things Gemology.
Robert Webster & Peter Read both from the British counterpart to GIA have written several books on the subjects of diamonds and gemology.
A quote from Gems: "Twinning may also occur locally within the crystal (diamond) producing "hard" spots which are frequently called "naats" or "knots".
I do not disagree that a surface reaching included crystal may also be a knot but the point is that the knot is oriented in a different direction than the facet that it is on and would be a hard spot and very difficult to polish. Twinning whisps are something entirely different.
That is a fairly large knot in that picture. I am interested to know what GIA clarity graded that stone?

 

[niceice]

----------------
On 3/19/2003 10:59:20 PM dimonbob wrote:
GIA is not the last word nor the only authority when it comes to all things Gemology.
Robert Webster & Peter Read both from the British counterpart to GIA have written several books on the subjects of diamonds and gemology.
A quote from Gems: "Twinning may also occur locally within the crystal (diamond) producing "hard" spots which are frequently called "naats" or "knots".
I do not disagree that a surface reaching included crystal may also be a knot but the point is that the knot is oriented in a different direction than the facet that it is on and would be a hard spot and very difficult to polish. Twinning whisps are something entirely different.
That is a fairly large knot in that picture. I am interested to know what GIA clarity graded that stone?
----------------

Right, however the original question posted asked "what is a knot on a GIA diagram" thus the explanation is based on the definition of a knot as defined by the GIA... We're not at the obvious and don't have the lab report in front of us, but seem to recall that it was an SI-1 or VS-2 graded stone...

 

[aggiefan]

Thank you all for your responses. The picture is worth a thousand words! The next person that searches for "knot" will find some good information!