July 21-28—ARDEN, NORTH CAROLINA: 16th Annual Western North Carolina Rockhound Roundup; Mountain Area Gem and Mineral Association; Camp Stephens, daily 8:30-5
Welcome to the GemologyOnline.com Forum
A non-profit Forum for the exchange of gemological ideas
It is currently Mon Jul 15, 2019 4:54 pm

All times are UTC - 4 hours




Post new topic Reply to topic  [ 18 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: Gem Quiz
PostPosted: Mon Jul 24, 2006 6:47 pm 
Offline
Platinum Member

Joined: Tue Nov 29, 2005 2:02 pm
Posts: 2647
This is a good portion of the face up view of this gem in darkfield lighting.

Identify the gem AND describe why it looks this way.

Image


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Mon Jul 24, 2006 7:09 pm 
Offline
Platinum Member

Joined: Sun Oct 16, 2005 12:42 pm
Posts: 2591
My first though is rain in a flux ruby. Intersections at 120 degrees.

_________________
Proud to be a DSN and JTV shopper, just love the guys!


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Mon Jul 24, 2006 7:25 pm 
Offline
Platinum Member

Joined: Tue Nov 29, 2005 2:02 pm
Posts: 2647
This is the stone in late afternoon natural roomlight.



Image


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Jul 25, 2006 6:45 pm 
Offline
Platinum Member

Joined: Tue Nov 29, 2005 2:02 pm
Posts: 2647
No other guesses eh? Can't say I blame you.

Doos gets at least partial credit, it is corundum. Although natural.
I have several pieces of this low quality material, each exhibits some interesting growth features.

Being translucent they don't make very good photo subjects as some of these features are so faint they just don't show up in enough detail to be visually helpful in the images.

The quiz stone tested as corundum. 1.76 approx. spot reading.It showed two fluorescent chromium lines in the red around 690, as well as general absorption in the yellow and most of the green. It has a weak to moderate red reaction to LWUV, inert to SW.

As you can see it is reddish purple with purple being the more dominant in normal light.

As for the appearance in the first image....I was hoping someone here could explain. It appears to have distinct color banding in one direction as well as distinct color zoning running at an oriented angle to the banding.
Don't know if this occured simultaneously or if it represents an interruption in growth and then new growth in a different crystal orientation.

Anyone here want to venture an opinion?
I've searched the www trying to find any similar images without luck.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Jul 25, 2006 11:37 pm 
Offline
Valued Contributor

Joined: Sun Oct 16, 2005 4:25 pm
Posts: 161
Location: Michigan, USA
There is a similar sapphire photo in the color plates of Matlin's Gem ID Made Easy. The caption say it's silk with needles intersecting at 60 degrees. Can't offer any more than that . . . :oops:


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Jul 27, 2006 11:55 am 
Offline
Valued Contributor
User avatar

Joined: Tue Oct 25, 2005 10:12 pm
Posts: 127
Location: Penang, Malaysia
I see fishy dye-like colour on the background...
Fishy colour banding from top to bottom...
Polysynthetic twinning from left to right...

that's what i see.....wrong? :?

_________________
~Knowledge is Power and Power Corrupts, so Study and be Evil~


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Jul 27, 2006 1:26 pm 
Offline
Valued Contributor

Joined: Sun Oct 16, 2005 4:25 pm
Posts: 161
Location: Michigan, USA
OK, Riniel, you made me look at it more closely and so, no, it doesn't look like the photo in GemIDME. Hmm, is that a dyed surface?


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Jul 27, 2006 1:57 pm 
Offline
Platinum Member

Joined: Tue Nov 29, 2005 2:02 pm
Posts: 2647
Dying could be a suspicion, but the broad patches of color are one directional. I have no reason to believe dye is involved. This stone is double cabbed both sides being rounded like a somewhat flattened jelly bean.

The pattern you see repeats itself on the flip side.

A more complete view of the stone in darkfield.

Image


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Jul 27, 2006 4:45 pm 
Offline
Gemology Online Royal Princess

Joined: Mon Oct 17, 2005 10:56 am
Posts: 6462
Location: The frozen north prairie :-/
Are you sure it isn't a jelly bean with swirls of undissolved sugar? :shock:


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Jul 27, 2006 5:12 pm 
Offline
Platinum Member

Joined: Tue Nov 29, 2005 2:02 pm
Posts: 2647
Nope, tastes just like corundum to me.

btw: I gave it good bath in acetone...cleaned it nicely with no change in appearance,or evidence of dye.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Jul 27, 2006 6:02 pm 
Offline
Valued Contributor

Joined: Sun Oct 16, 2005 4:25 pm
Posts: 161
Location: Michigan, USA
OK, if one sees the same thing on both sides and it is double cabbed, then is it a doublet and what you are seeing is the adhesive?


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Jul 27, 2006 6:31 pm 
Offline
Platinum Member

Joined: Tue Nov 29, 2005 2:02 pm
Posts: 2647
No, No, this isn't any kind of trick question. It is corundum and not an assembled stone of any sort.

I'm just trying to get a definitive answer on the banding and zoning(?).

The cause and relationship if any.

Just a learning exercise for us. :)


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Jul 27, 2006 10:39 pm 
Offline
Valued Contributor

Joined: Sun Oct 16, 2005 4:25 pm
Posts: 161
Location: Michigan, USA
OK, I saw in Photoatlas of Inclusions I in the Corundum section many photos and references discussing the zone effect in Burma and Sri Lanka stones. And the photos look similar there too. Does that sound plausible? But I don't think that explains the "banding", though I could look a little closer at the atlas if you think this is the right track.

Modo, it looks like a used Ricola cherry cough drop to me!


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Fri Jul 28, 2006 6:21 pm 
Offline
Platinum Member

Joined: Tue Nov 29, 2005 2:02 pm
Posts: 2647
I think if Riniel can catch Vincent in a slow moment, he may have some insight.

Anyone that looks at corundum on a daily basis, in various locations and a wide range of quality has probably seen similar characteristics before.

Just need them properly defined.

This isn't jewelry quality stuff, just material that's telling a story and I don't know the ending yet.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Fri Jul 28, 2006 10:33 pm 
Offline
Valued Contributor
User avatar

Joined: Tue Oct 25, 2005 10:12 pm
Posts: 127
Location: Penang, Malaysia
I think Vincent is still on his trip...he should back soon...
maybe he'll visit this page when he gets back....

_________________
~Knowledge is Power and Power Corrupts, so Study and be Evil~


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 18 posts ]  Go to page 1, 2  Next

All times are UTC - 4 hours


Who is online

Users browsing this forum: No registered users and 1 guest


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