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 8:24 am

All times are UTC - 4 hours




Post new topic Reply to topic  [ 19 posts ]  Go to page Previous  1, 2
Author Message
 Post subject:
PostPosted: Thu Oct 29, 2009 9:27 am 
Offline
Gold Member
User avatar

Joined: Mon Apr 16, 2007 12:05 am
Posts: 1499
You can just explain during the chat! :wink:


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Oct 29, 2009 10:10 am 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
The GIA lists a Chelsea in a paragraph in a section called "Occasional Tests", Chapter 35, Gem Identification Course.
Quote:
The Chelsea Color Filter is used to detect dyes in certain gems, to indicate the coloring agent in some gems and to separate some gem materials from common imitations. It is a simple, inexpensive device, and thus, a popular piece of gem testing equipment in jewelry stores. Some dealers who examine large quantities of gems fid the Chelsea Color Filter handy for detecting synthetic blue spinels that sometimes get slipped into parcels of aquamarine.
RESULTS: The following are some color Filter reactions that may help you identify certain gems.
-Synthetic blue spinel: pink to red
-Synthetic Blue Quartz: pink
-Blue Cobalt Glass: pink to red
-Dyed Green Chalcedony: red to orange-red to pinkish orange
-Dyed Blue Chalcedony: red to pink to pinkish orange
-Dyed Blue Howlite: pink or red
NOTE In addition to the materials listed above, some others may change color under the Chelsea color filter-but this may or may not aid in identification. Emerald turns red, for example-but, so does synthetic emerald. Demantoid garnets and some green zircons look pinkish or reddish through the filter, and thus could be confused.Thus, although the Chelsea color filter may be a useful supplemental test, the results give only an indication, not proof of a stone's identity


When I attended DGemG, it was never mentioned.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Oct 29, 2009 1:39 pm 
Offline
Valued Contributor
User avatar

Joined: Mon Feb 02, 2009 8:15 pm
Posts: 112
Location: London, UK
Interesting. I went to the Gem-A conference a few weeks before, Antoinette Matlins (she was one of the speaker, and her topic was "After 75 years, the Chelsea Colour Filter still proves its worth") has convinced a lot of the attendees that CCF is useful.

I am definitely here on Sunday for Brian's talk. :)

P


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Tue Nov 03, 2009 12:45 am 
Offline
Gold Member
User avatar

Joined: Mon Apr 16, 2007 12:05 am
Posts: 1499
I will be out of town this coming weekend. If it is of continuing interest, we'll try to tackle the "color center electron trap" the following weekend. The whiteboard was pretty effective this past chat, so we'll use it again.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 19 posts ]  Go to page Previous  1, 2

All times are UTC - 4 hours


Who is online

Users browsing this forum: No registered users and 5 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