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Characteristics: Knot ... what the?

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BecomingACutNerd

Rough_Rock
Joined
Jun 27, 2003
Messages
13
First of all ... I''ve been lurking here for a few weeks, and my name says it all. You people are turning me into a cut snob! I go to sleep at night with visions of dancing crown and pavilion angles in my head. Now if I could just get that HCA tool on a palm pilot, I''d be armed and dangerous for B&M''s! Guess I''ll just stick with the net ...

Anyway, I''ve located a couple of diamonds on BN. Oddly enough, for that site atleast, the GIA certs have the Sarin''s on them, but they''ve cut the inclusion diagrams off. And under the clarity field, they''ve included another field which I haven''t seen before: Characteristics. One is Crystal, the other is Knot. Is this as bad as it sounds? The diamonds score good on the HCA, and both are selling for a decent price. I was just curious, because everything else about the diamonds sounds pretty good.

Specs:
.92c
H
VS2
56% Table
61.5% Depth
34.5'' Crown
40.6'' Pavilion
EX/EX
Characteristics: Knot
Faint Flourescence
HCA = .7 EX EX EX VG
$5014

.90c
H
VS2
54% Table
62.3% Depth
34.6'' Crown
40.9'' Pavilion
EX/EX
Characteristics: Crystal
Faint Flourescence
HCA = 1.7 EX EX EX VG
$5029
 

mike04456

Brilliant_Rock
Joined
Nov 20, 2002
Messages
1,441

----------------
On 6/27/2003 3:27:48 PM BecomingACutNerd wrote:
One is Crystal, the other is Knot. Is this as bad as it sounds?

----------------
Not really. They are more or less the same thing; the only difference is the position. A "crystal" means there is an included crystal inside the diamond. It may be another diamond the surrounding diamond grew over, it may be something else like a garnet or diopside. A "knot" is just a crystal that reaches the surface. In most cases it's another diamond because anything else won't survive the cutting process... it will fall out and create a cavity.

Since both stones are GIA VS2s, that means both crystal and knot are very very small. Almost certainly not eye-visible. You might ask where they are located, i.e., under the table (unlikely), near the girdle, or down in the pavilion.
 

BecomingACutNerd

Rough_Rock
Joined
Jun 27, 2003
Messages
13
Thanks for the reply! I'll request more information on these two. I just thought it was odd that the GIA report would make specific reference to it in the report under the clarity.
 

mike04456

Brilliant_Rock
Joined
Nov 20, 2002
Messages
1,441
A macle is a diamond twin. Twinning occurs in a lot of other minerals, such as spinel and garnet, and can take a lot of different forms. Sometimes you get two crystals growing through each other, sometimes you've got two different crystal forms growing from the same point. Other times, it's a result of the geologic conditions changing during crystal growth. That's believed to be what happens with macles. Macles would have grown up to be nice octahedrons except that something caused the crystallizing carbon to change direction. The crystal form of a macle is actually a corrupted octahedron; if you slice through it across the twinning plane and turn one half 180 degrees, you'll get an octahedron, though not a very pretty one.

For any more than that, you're going to have to consult a mineralogist.
But here's a couple of nice little sites I found on general diamond geology:

http://www.canadianrockhound.com/2002/01/cr0206101_diamonds.html

http://www.amnh.org/exhibitions/diamonds/composition.html

Have fun.
 

pyramid

Ideal_Rock
Premium
Joined
Nov 10, 2002
Messages
4,607
Date: 6/27/2003 3:43:21 PM
Author: mike04456


----------------

On 6/27/2003 3:27:48 PM BecomingACutNerd wrote:

One is Crystal, the other is Knot. Is this as bad as it sounds?


----------------
Not really. They are more or less the same thing; the only difference is the position. A ''crystal'' means there is an included crystal inside the diamond. It may be another diamond the surrounding diamond grew over, it may be something else like a garnet or diopside. A ''knot'' is just a crystal that reaches the surface. In most cases it''s another diamond because anything else won''t survive the cutting process... it will fall out and create a cavity.


Since both stones are GIA VS2s, that means both crystal and knot are very very small. Almost certainly not eye-visible. You might ask where they are located, i.e., under the table (unlikely), near the girdle, or down in the pavilion.

___________


Why would a garnet or diopside not survive the cutting process like a diamond knot would, does it fall out because it has a different form of crystalization and so does not bond to the diamond crystal when it grows around it or would it break into pieces before falling out?
 
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