What are the surface striations

[pyramid]

http://www.johnbetts-fineminerals.com/jhbnyc/gifs/36171.htm


The rough diamond pictured here, can one of the experts tell me if 'the surface striations' mentioned and shown on the diamond is different from surface graining or the same thing?

I am thinking it is not surface graining because even at that magnification the lines look too thick.

However, because of the orientation of it going around the stone it must have something to do with graining too?




From further reading it seems to be related to the crystal habit.

The most common cause of striations are the convergence or juxtaposition of two crystal faces. One of the faces gets truncated or "overtaken" by the other, but manages to leave its mark in the form of an almost imperceptible edge or stria. This edge is repeated again and again as the mineral grows and can fill an entire face with these tiny edges or striations.

 

[pyramid]

Is the answer I found correct in this case? Any experts know.

 

[RockDoc]

If I understand and interpret what you''re saying correctly, I''d agree with you.


However, what you may be seeing is a part of the diamonds skin as the crystal formed.

To really ascertain if this is a consideration - windows should be polished to see what happens to those lines your wrote about. In looking at the photo and making and opinion ( which is a tad risky ) I''d think those may polish out, but one never totally knows until the polishing is done.

In looking at the other stones on the site, they have interesting crystal forms, but may not be the best candidates for cutting and faceting. It is difficult on some of even the "gem quality" stones to know what inclusions are in the stones, and generally they aren''t mentioned.

So if you''re being tempted by the price of the rough to venture into possibly having one cut, I''d sort of encourage you to look at better color rough.

If you want the stone to have a unique rough crystal, some of the shapes are nice on his site. However, I''ve seen better quality ones.

Hope this helps.

Rockdoc

 

[pyramid]

Thanks Rockdoc. No I am not considering buying, I just found the site on an internet search and thought it was interesting to see the shapes and wondered about the striations. When I buy it will be a polished stone for a ring. I like the look of the rough stones but although not too expensive I feel they would just sit in a box for years, so I won''t be buying, I am just interested in them.

 

[RockDoc]

Actually Pyraimid


You can set a nice piece of rough into a jewelry design and have something that is quite unusual.

Well formed octahedrons are good for this.

Lazare Kaplan had a great design years ago with a brown- to greenish large ( 5-20 carat ) octahedron set at its tips in a sort of clamp looking design of 18 karat yellow gold that had a leather necklace. The diamond crystals were similar in quality to the ones that are on the site you mentioned.

I''ve seen some octahedron smooth crystals that were not included at all and high color too set in jewelry. Interesting designs and definately distinctive and different.

Rockdoc

 

[pyramid]

Yes I thought about a pendant but at the moment all spare money needs to go to the ring. Something to keep in mind though because I do like the look of the rough diamond too.