January 24 Through February 4—TUCSON, ARIZONA: Annual show
Welcome to the GemologyOnline.com Forum
A non-profit Forum for the exchange of gemological ideas
It is currently Thu Mar 28, 2024 5:57 pm

All times are UTC - 4 hours




Post new topic Reply to topic  [ 7 posts ] 
Author Message
 Post subject: Unusual Crystal
PostPosted: Wed May 22, 2019 2:04 pm 
Offline
Gemology Online Veteran
User avatar

Joined: Tue Jan 31, 2006 12:38 pm
Posts: 894
Location: N.J.
Kind of an unusual surface on this 10 ct. orange diamond up for auction.


Attachments:
Screenshot_20190522-133834_Samsung Internet.jpg
Screenshot_20190522-133834_Samsung Internet.jpg [ 538.58 KiB | Viewed 2996 times ]

_________________
Nick
Top
 Profile  
Reply with quote  
 Post subject: Re: Unusual Crystal
PostPosted: Wed May 22, 2019 4:48 pm 
Offline
Moderator: Lapidary Diamonds
User avatar

Joined: Mon Aug 20, 2012 11:32 pm
Posts: 1747
Location: Florida, United States
A Congo cube. The surface is a colored coating. Under the coating it may be clear or not, flawed or not.

_________________
http://adamasfacet.com


Top
 Profile  
Reply with quote  
 Post subject: Re: Unusual Crystal
PostPosted: Wed May 22, 2019 6:05 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
First time I heard of a Congo Cube. Thanks Thomas.

Is the coating diamond as well?
Looks like a secondary crystallization.
Why are all the diamonds exhibiting this secondary crystallization?
If the coating is diamond, it appears that they are all randomly oriented.

Any literature on this?


Top
 Profile  
Reply with quote  
 Post subject: Re: Unusual Crystal
PostPosted: Thu May 23, 2019 8:52 pm 
Offline
Gold Member

Joined: Mon May 26, 2014 9:42 pm
Posts: 1033
I was talking to someone who collected diamond crystals at Tucson, and he called these "sugar cubes" and said that occasionally they had a clean octahedron inside them. He actually had one there where the octahedron was exposed.


Top
 Profile  
Reply with quote  
 Post subject: Re: Unusual Crystal
PostPosted: Fri May 24, 2019 5:16 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
I did a search and they seem available. Octahedron underneath? Splain that Ricky.


Top
 Profile  
Reply with quote  
 Post subject: Re: Unusual Crystal
PostPosted: Sat May 25, 2019 3:51 pm 
Offline
Gold Member

Joined: Mon May 26, 2014 9:42 pm
Posts: 1033
Can't really explain it. He had an example: a clean octahedral diamond surrounded by what looked like "sand" made out of diamond. The shape of the exterior is a cube. He told me they were called "sugar cubes" and they certainly looked like it. He said that sometimes when you dig into them, there is a clean octahedral diamond in them, and he had one with the edge worn away, where you could see the octahedral diamond crystal inside. if you go here: http://whistleralley.com/polyhedra/cube10.gif you can see how cutting the corners off a cube leaves an octahedron. (and you can go the other way, too.)
Image


Top
 Profile  
Reply with quote  
 Post subject: Re: Unusual Crystal
PostPosted: Sat May 25, 2019 6:33 pm 
Offline
Gemology Online Veteran
User avatar

Joined: Tue Jan 31, 2006 12:38 pm
Posts: 894
Location: N.J.
Here's a couple more from the same Kasai river alluvial Congo location. At about a hundred bucks a carat, would be nice if they were cuttable to any size.


Attachments:
20190525_182314.jpg
20190525_182314.jpg [ 352.71 KiB | Viewed 2899 times ]

_________________
Nick
Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 7 posts ] 

All times are UTC - 4 hours


Who is online

Users browsing this forum: No registered users and 10 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
Gemology Style ported to phpBB3 by Christian Bullock