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 4:26 pm

All times are UTC - 4 hours




Post new topic Reply to topic  [ 5 posts ] 
Author Message
 Post subject: darkfield ?
PostPosted: Wed Sep 05, 2012 3:15 pm 
Offline
Established Member
User avatar

Joined: Tue Aug 16, 2011 11:42 pm
Posts: 27
Hi

I was looking at some corundum under the darkfield loupe. I was thinking maybe I could see curved straie for the synthetics and something else for the natural. However what I am seeing is some lines that are parallel to the facets, which look like maybe facets that aren't as polished? Should I be able to see growth straie in 10x darkfield?

Thanks!
-Neal


Top
 Profile  
Reply with quote  
 Post subject: Re: darkfield ?
PostPosted: Wed Sep 05, 2012 4:50 pm 
Offline
Site Admin
User avatar

Joined: Fri May 12, 2006 11:24 am
Posts: 7523
Location: Rome, Italy
hi

nealc wrote:
Should I be able to see growth straie in 10x darkfield?


growth lines of different color intensity can be easily visible even at naked eye sometimes, it depends by the stone.

ciao
alberto

_________________
GemmoRaman-532 - GemmoFTIR - GemmoSphere - EXA


Top
 Profile  
Reply with quote  
 Post subject: Re: darkfield ?
PostPosted: Thu Sep 06, 2012 1:24 pm 
Offline
New to the Forum or The Quiet Type

Joined: Mon Jun 25, 2012 11:04 am
Posts: 9
Doesn't the direction in which one looks at the stone potentially alter the appearance of growth bands? My understanding is that curved bands can potentially look straight if you view the lines parallel to crystal face in which they were formed.


Top
 Profile  
Reply with quote  
 Post subject: Re: darkfield ?
PostPosted: Sat Oct 20, 2012 8:53 pm 
Offline
Valued Contributor
User avatar

Joined: Wed Jun 15, 2011 8:29 am
Posts: 123
Location: London
Of course the direction matters when looking at the stone, that's why you have to check it from all sides. Only along one plane growth lines will clearly be visible, it's like looking for circular shape with a glass- you have to look right down it. Curved lines won't look straight from different direction because they are layers, like in a tree, they may appear straightish if stone is coming from large boule (talking about synthetics). In natural stones the growth lines will follow hexagonal shape or any part of it ( like straight line, two lines meeting at an angle etc.) Hard to tell without good pictures what we are talking about here...

_________________
Treasurion Gems & Jewellery

Gems & Jewellery Blog

Top
 Profile  
Reply with quote  
 Post subject: Re: darkfield ?
PostPosted: Sun Oct 21, 2012 7:52 am 
Offline
Site Admin
User avatar

Joined: Fri Apr 17, 2009 3:53 pm
Posts: 2049
Location: Sweden
There can also be "polishing" lines on the facets as you mention. They are at the surface and is best viewed by reflected light coming in sideways. It can be seen through the stone sometimes but should be pretty easily distinguishable from growth phenomena.

_________________
_____________
Conny Forsberg


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC - 4 hours


Who is online

Users browsing this forum: No registered users and 14 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