June 22-25: Sainte-Marie-aux-Mines:International Mineral & Gem Show
Welcome to the GemologyOnline.com Forum
A non-profit Forum for the exchange of gemological ideas
It is currently Wed Jun 28, 2017 5:05 pm

All times are UTC - 4 hours




Post new topic Reply to topic  [ 14 posts ] 
Author Message
 Post subject: New Opal (Homogeneously Crystalized)
PostPosted: Tue Mar 14, 2017 4:46 pm 
Offline
Established Member

Joined: Wed Nov 09, 2011 5:35 am
Posts: 34
Just for your information:

I’m very happy to see that now it is possible to prepare opals without columnar patterns.

These opals with homogeneously crystallized silica particles in a polymer matrix (= HoC-Si-Pol) don’t show a columnar pattern typical for opals grown by sedimentation.
With big polygonal crystallites of 2-3 mm these multicolored opal can be produced in big blocks and different body colors.

Image

For more information please visit:

http://www.synthetic-opals.com

By use of a modified technology now fine crystalline „Aurora Opals“ are available:

http://www.aurora-opals.com

Image

_________________
http://www.pinfire.de


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Mon Mar 20, 2017 2:24 pm 
Offline
Gemology Online Veteran
User avatar

Joined: Wed Dec 30, 2009 11:44 am
Posts: 507
Location: PAKISTAN-Peshawar
:shock: :shock: :shock:

_________________
Gemology for everyone.
HUK


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Mon Mar 20, 2017 7:25 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 17934
Location: San Francisco
Quote:
homogeneously crystallized silica particles in a polymer matrix


By definition, a synthetic gem is a man-made material with essentially the same chemical composition, crystal structure and optical and physical properties as the natural gem material.

I don't think your stone can be called synthetic opal.


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Mon Mar 20, 2017 8:45 pm 
Offline
Moderator
User avatar

Joined: Mon Apr 02, 2012 9:31 pm
Posts: 2489
Location: North Carolina
I think almost all man-made opal is polymer impregnated. It is one of those odd edge-cases, since natural opal can be polymer impregnated as well in post, and it would still be opal. Opal beads can also crystallize after formation so that isn't necessarily a disqualifying factor either.


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Mon Mar 20, 2017 10:56 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 17934
Location: San Francisco
Fair enough.....


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Mon Mar 20, 2017 11:55 pm 
Offline
Moderator
User avatar

Joined: Mon Apr 02, 2012 9:31 pm
Posts: 2489
Location: North Carolina
I agree though that it is a weird edge case and has some definite differences to natural material. Hopefully that will make for easier identification, given how different this looks from traditional synthetic material.


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Tue Mar 21, 2017 1:15 pm 
Offline
Gold Member

Joined: Mon May 14, 2007 11:00 am
Posts: 1115
Location: Monterey, CA
Just call it artificial. :)
The word synthetic has no meaning relative to value.


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Tue Mar 21, 2017 4:25 pm 
Offline
Moderator
User avatar

Joined: Mon Apr 02, 2012 9:31 pm
Posts: 2489
Location: North Carolina
Bill Hanneman wrote:
Just call it artificial. :)
The word synthetic has no meaning relative to value.

That's not true when it comes to opal. Metal foil in glass or resin could look superficially similar in a photo but in person the resemblance is slight.


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Wed Mar 22, 2017 5:50 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 17934
Location: San Francisco
I would tend to call these opals an artificial product as well.

Like CZ.
Yes, Baddeleyite (ZrO2 occurs naturally, but it never contains the dopants (lower-valence oxides like Ca
O, MgO, or Y2O3 which make it crystallize in the cubic system.


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Wed Mar 22, 2017 11:44 pm 
Offline
Valued Contributor

Joined: Sat Nov 05, 2016 11:29 am
Posts: 127
I would call it a simulant, as it is not an opal.
A synthetic, or lab created opal would largely have the same characteristics as natural opal, which this clearly does NOT, as it is roughly 80% plastic, vs. 20% SiO2, and its specific gravity is horrendously off (much lighter than real opal) ...


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Thu Mar 23, 2017 12:25 pm 
Offline
Established Member

Joined: Wed Nov 09, 2011 5:35 am
Posts: 34
Is it only important how to call the material?

Nobody wants to know what „homogeneously crystallized“ means?

Here's an example, which also shows that a material with play-of-color does not necessarily have to be solid:

https://www.youtube.com/watch?v=rvNmH96dqAw

_________________
http://www.pinfire.de


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Thu Mar 23, 2017 4:40 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 17934
Location: San Francisco
This is a professional gemological forum, Goldberg.
Yes, as gemologists, mineralogists and chemists we DO want to know what "homogeneously crystallized“ is intended to mean in regards to opal and whether or not it is just a deliberately obfuscating description.

Pretty video on crystalline suspension of colloidal silica particles but what does that have to do with calling a predominately plastic product a synthetic opal?


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Thu Mar 23, 2017 6:59 pm 
Offline
Moderator
User avatar

Joined: Mon Apr 02, 2012 9:31 pm
Posts: 2489
Location: North Carolina
When they say "colloidal crystal" on the vodeo I believe they are referring to the concept of a photonic crystal (ie an orderly arrangement of particles that diffracts light the way a crystal diffracts xrays). It would be weord to use the term "homogenously crystallized" to refer to that phenomenon.
I could see synthetic vs simulant going either way, but we already call other resin-infused products synthetics, and since it is used as a binder for silica particles arranged in the same way as in a natural opal I don't mind it much. One way or another it is quite different from lesser imitations. Seems like the end product might be like taking one of those Ethiopian chalk opals and soaking it with resin.
Fortunately that should make distinguishing them relatively easy, which is always a big plus.


Top
 Profile  
Reply with quote  
 Post subject: Re: New Opal (Homogeneously Crystalized)
PostPosted: Thu Mar 23, 2017 7:58 pm 
Offline
Gold Member
User avatar

Joined: Thu Jan 24, 2008 4:01 pm
Posts: 1734
Location: Pine City, NY and Dothan, AL
"Homogeneously crystallized“ just means that the nucleation starts within the mix, rather than from the surface. I think this is just another example of using big words to impress potential customers. As for the simulant/synthetic question, I'll leave that to you gemologists :-) It's obviously not natural opal.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 14 posts ] 

All times are UTC - 4 hours


Who is online

Users browsing this forum: No registered users and 2 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