CIBJO releases Gemmological Special Report: considers process of separating measurable facts from opinion; See Gemological Articles below.
Welcome to the GemologyOnline.com Forum
A non-profit Forum for the exchange of gemological ideas
It is currently Fri Nov 22, 2019 8:02 am

All times are UTC - 4 hours




Post new topic Reply to topic  [ 52 posts ]  Go to page Previous  1, 2, 3, 4  Next
Author Message
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Thu Nov 24, 2011 4:45 am 
Offline
Established Member

Joined: Wed Nov 09, 2011 5:35 am
Posts: 36
Only preliminary tests were done. Although promising, a lot of more samples and tests are necessary to get reproducible results

And a lot of open questions remain: changes in RI, density, open porosity, final water content…..

But these examinations will be done in my own interest, because (this was the reason that I’ve posted the topic) I got the message of an opal vendor (hydrophane opals from Ethiopia) that if these opals can be brought to the market he intends to offer the stones only as “non-hydrophane” and, because colour and clarity remain unchanged, without further description, properties and stability are irrelevant.

To know it for sure if and how the opals should be declared I’ve decided to ask the experts here…….

Finally it seems that I've come to the right place and want to thank all of you for your answers, hints, advices


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Thu Nov 24, 2011 10:31 am 
Offline
Gold Member
User avatar

Joined: Thu May 29, 2008 8:32 am
Posts: 1718
Location: Suwanee, GA US
Non-hydrophane as the only description would be deceptive. They have been treated.

According to your picture, you are changing the chemical bonds on the molecules much like some of the infusion processes or bombarding it with particles using Cesium-60. So this is not a stabilizer. Jay and Barbra are asking the questions because someone who even cuts it will probably use acetone or alcohol as solvents. While water is a very aggressive solvent, acetone will affect a wide range of hydrocarbons including glues, stabilizers, and oils.

_________________
George Ellis
www.faceting.biz


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Thu Nov 24, 2011 12:08 pm 
Offline
Established Member

Joined: Wed Nov 09, 2011 5:35 am
Posts: 36
I will do tests in the following order :)

BBQ-test, dishwater-test, sunlight-test, alcohol-test......................

_________________
http://www.pinfire.de


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Thu Nov 24, 2011 2:06 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 19909
Location: San Francisco
Quote:
But if you're interested in this topic I recommend:

"The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties and Biochemistry of Silica"
written by Ralph K. Iler


Perhaps, we'd be more interested in just a simple, yet concise, description of what you're doing and the subsequent stability of the process. :D


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Thu Nov 24, 2011 6:32 pm 
Offline
Established Member

Joined: Wed Nov 09, 2011 5:35 am
Posts: 36
I doubt that visitors of a forum dedicated to gemstones are interested in details about "surface modification of colloidal particles"

_________________
http://www.pinfire.de


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Thu Nov 24, 2011 7:54 pm 
Offline
Valued Contributor
User avatar

Joined: Mon Nov 05, 2007 8:01 pm
Posts: 235
goldberg wrote:
I doubt that visitors of a forum dedicated to gemstones are interested in details about "surface modification of colloidal particles"


I think you are going to be very surprised on this.

goldberg wrote:
Does it mean that the non-hydrophane opals must be declared only as "treated" if a change of the optical properties can be observed after treatment, otherwise not?


You have mentioned several times that color and clarity are not affected by this treatment, yet both your original post and your pictures show a visible increase in transparency, which is an optical property.

_________________
My brand new website: www.beatrizfortes.com


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Fri Nov 25, 2011 4:46 am 
Offline
Site Admin
User avatar

Joined: Fri Apr 17, 2009 3:53 pm
Posts: 2049
Location: Sweden
Goldberg you bet we are interested. Many people around here are trade professionals as well as hard working gemologists. We all want to know.

_________________
_____________
Conny Forsberg


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Fri Nov 25, 2011 4:15 pm 
Offline
Gold Member
User avatar

Joined: Fri Oct 12, 2007 10:22 pm
Posts: 1117
Location: Virginia
Are you treating rough or finished stones or both?

_________________
Soil is not dirt.
http://hmmdesign.net


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Fri Nov 25, 2011 4:34 pm 
Offline
Site Admin

Joined: Thu Jan 05, 2006 4:27 pm
Posts: 1750
I have to agree with scaramouche and conny on this. WE ARE INTERESTED.

You haven't disclosed to us exactly what the treatment is yet you seem to conclude from the answers given that some sort of bull like "non hydrophane" would be acceptable as a treatment description...I cry NO.

You either describe the treatment and disclose it to buyers or you bullshit the buyers by using some ambiguous term that you have concluded is acceptable due to your own interpretation of the answers given in your post. This is simply sophistry and seems to me like you are trying to use us as an acceptable "expert opinion" on which to base a deceptive description. (Please excuse me if I have this wrong)

Full disclosure...which is the ONLY acceptable practise as far as I am concerned seems to be something to be avoided rather than supported according to your posts.

Please either describe your treatment (honestly we are interested) or make your own mind up about what to disclose to consumers. We are not here to make you feel justified in using your own treatment description

More details on the treatment and less discussion on what to call it would do me fine...do ye ken

Frank


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Sat Nov 26, 2011 1:08 am 
Offline
Established Member

Joined: Wed Nov 09, 2011 5:35 am
Posts: 36
empress wrote:
Are you treating rough or finished stones or both?


I've started with rough stones, but changed to finished opals to save time (less volume).


Frank wrote:
Full disclosure...


Yes, of course

_________________
http://www.pinfire.de


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Sat Nov 26, 2011 1:09 pm 
Offline
Gold Member
User avatar

Joined: Thu May 29, 2008 8:32 am
Posts: 1718
Location: Suwanee, GA US
goldberg wrote:
I doubt that visitors of a forum dedicated to gemstones are interested in details about "surface modification of colloidal particles"

Maybe you should go look at some of the threads on Andesine on this forum. We have a wide range of folks including those that are doing a wide range of treatments (I need to get some cedar oil and an evacuation device this month to treat an emerald).

This is the gem nerd forum on the web. Shoot, go look at the inclusion pictures section, another fine example.

_________________
George Ellis
www.faceting.biz


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Sat Nov 26, 2011 2:57 pm 
Offline
Established Member

Joined: Wed Nov 09, 2011 5:35 am
Posts: 36
gsellis wrote:
(I need to get some cedar oil and an evacuation device this month to treat an emerald).


An evacuation device?

Why not using a simple exsiccator and a oil-pump?

I think you can get all the things you need here:

http://www.labexchange.com/en/home/

I will read the Andesine threads carefully....

Okay, this leads to another topic and is not about opal treatment anymore.

_________________
http://www.pinfire.de


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Sat Nov 26, 2011 5:29 pm 
Offline
Established Member

Joined: Wed Nov 09, 2011 5:35 am
Posts: 36
gsellis wrote:
(I need to get some cedar oil and an evacuation device this month to treat an emerald).


If you are interested to treat in emerald, I would prefer an optical glue. There are several companies. They offer such glues in a wide range of "index of refraction" and viscosity. It will be suited for a lot of materials and is better than oil.

_________________
http://www.pinfire.de


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Sat Nov 26, 2011 5:45 pm 
Offline
Valued Contributor

Joined: Wed Oct 22, 2008 5:00 am
Posts: 344
Location: Finland
People want to use oil instead of modern chemistry because it's traditional and widely accepted.

_________________
GemmoRaman GemmoFtir GemmoSphere


Top
 Profile  
Reply with quote  
 Post subject: Re: Water-repellent non-hydrophane opal (Welo/Ethiopia)
PostPosted: Sat Nov 26, 2011 5:49 pm 
Offline
Established Member

Joined: Wed Nov 09, 2011 5:35 am
Posts: 36
Frank wrote:
This is simply sophistry and seems to me like you are trying to use us as an acceptable "expert opinion" on which to base a deceptive description. (Please excuse me if I have this wrong)

Full disclosure...which is the ONLY acceptable practise as far as I am concerned seems to be something to be avoided rather than supported according to your posts.

Please either describe your treatment (honestly we are interested) or make your own mind up about what to disclose to consumers. We are not here to make you feel justified in using your own treatment description


As I have told it more than once: I WILL DESCRIBE THESE OPALS AS TREATED.......

I WILL NOT USE MY OWN DESCRIPTION!

I'm fed up with it!!!

The question was how to describe these opals and which words are clear, descriptive, and according to the standards.

Now I know it, that's all.........

_________________
http://www.pinfire.de


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 52 posts ]  Go to page Previous  1, 2, 3, 4  Next

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