Time to catch up on reading, lapidary projects and binge watching TV. Stay home. Stay well.
Welcome to the GemologyOnline.com Forum
A non-profit Forum for the exchange of gemological ideas
It is currently Thu Apr 09, 2020 12:39 am

All times are UTC - 4 hours




Post new topic Reply to topic  [ 13 posts ] 
Author Message
 Post subject: How to identify natural amethyst vs heated amethyst
PostPosted: Sat Mar 21, 2020 2:34 pm 
Offline
Active Member

Joined: Mon Sep 03, 2012 11:32 am
Posts: 69
Hi
How can we differentiate between a heated amethyst and a natural non heated one.
Is it easy to identify without microscope using a loupe?


Top
 Profile  
Reply with quote  
 Post subject: Re: How to identify natural amethyst vs heated amethyst
PostPosted: Sat Mar 21, 2020 3:03 pm 
Offline
Valued Contributor

Joined: Wed Sep 15, 2010 4:12 am
Posts: 109
Location: Belgium
heated amethyst is yellow/brown :lol:

_________________
Marc
http://www.gemsdat.be/engels.htm


Top
 Profile  
Reply with quote  
 Post subject: Re: How to identify natural amethyst vs heated amethyst
PostPosted: Sat Mar 21, 2020 5:00 pm 
Offline
Gemology Online Veteran

Joined: Thu May 12, 2016 2:18 am
Posts: 739
If you are talking about heating to lighten the color a little, then I don't think there is a definitive way to tell.

If you are talking about Amethyst that has been heated to Citrine then the key is the dichroscope.

The iron in Amethyst and natural Citrine acts in the typical manner of trace elements in the crystal lattice. It changes the absorption spectrum to create the color. Therefore the color is influence by the crystal orientation, and exhibits dichroism. It is obvious and easy to check.

In Amethyst that has been heated to Citrine, the iron has been oxidized by the heat treatment. In other words it has rusted into a yellow to brown color. Since this oxidized iron is now basically acting as a stain rather than integrated in the crystal structure, it doesn't show dichroism. It is stained equally in all crystal directions.

I hope that answers your question.


Top
 Profile  
Reply with quote  
 Post subject: Re: How to identify natural amethyst vs heated amethyst
PostPosted: Sun Mar 22, 2020 3:08 am 
Offline
Active Member

Joined: Mon Sep 03, 2012 11:32 am
Posts: 69
Thanks for the knowledge.
I am asking about the light purple colored amethyst heated/radiated to intensify color into dark purple . Is it possible? If its the case then can we identify it?


Top
 Profile  
Reply with quote  
 Post subject: Re: How to identify natural amethyst vs heated amethyst
PostPosted: Sun Mar 22, 2020 12:05 pm 
Offline
Gemology Online Veteran

Joined: Thu May 12, 2016 2:18 am
Posts: 739
No, you heat over dark Amethyst to lighten it, as far as I know there is no way to darken light Amethyst.

When you irradiate quartz it turns to brownish to blackish. This may give it a darker tone, but it also muddies the color and produces unattractive stones. When you heat the stones you can remove the irradiated color back to the original color.

You can heat all Amethyst to near colorless.


Top
 Profile  
Reply with quote  
 Post subject: Re: How to identify natural amethyst vs heated amethyst
PostPosted: Sun Mar 22, 2020 2:27 pm 
Offline
Active Member

Joined: Mon Sep 03, 2012 11:32 am
Posts: 69
So, a too dark amethyst heated to reduce color slightly. i.e much appealing color then it will show dichroism.


Top
 Profile  
Reply with quote  
 Post subject: Re: How to identify natural amethyst vs heated amethyst
PostPosted: Sun Mar 22, 2020 3:08 pm 
Offline
Moderator
User avatar

Joined: Mon Apr 02, 2012 9:31 pm
Posts: 3546
Location: North Carolina
I wouldn't worry about treatment on amethyst. Those treatments that are possible aren't really detectable, and the real enemy is the widespread undisclosed synthetic amethyst which have flooded the market.

_________________
https://www.etsy.com/shop/angryturtle


Top
 Profile  
Reply with quote  
 Post subject: Re: How to identify natural amethyst vs heated amethyst
PostPosted: Sun Mar 22, 2020 3:17 pm 
Offline
Gemology Online Veteran

Joined: Thu May 12, 2016 2:18 am
Posts: 739
Yes, the synthetic Amethyst is not easy for most to detect, and a huge amount of this is on the market being sold as natural. The big problem is that at the price Amethyst sells for it is most often not worth proving natural/synthetic in cut stones.

I buy my Amethyst (Ametrine, Citrines, Prasiolite) rough direct from the mine either in Rwanda/Zambia or Brazil/Uruguay/Bolivia so I know the origin and treatments applied. But once the stones are cut and on the market who really knows.


Top
 Profile  
Reply with quote  
 Post subject: Re: How to identify natural amethyst vs heated amethyst
PostPosted: Mon Mar 23, 2020 2:26 am 
Offline
Active Member

Joined: Mon Sep 03, 2012 11:32 am
Posts: 69
Thanks for the info.
A synthetic amethyst can only be detected via microscope?


Top
 Profile  
Reply with quote  
 Post subject: Re: How to identify natural amethyst vs heated amethyst
PostPosted: Mon Mar 23, 2020 10:40 am 
Offline
Gemology Online Veteran

Joined: Thu May 12, 2016 2:18 am
Posts: 739
No a microscope won't do it. If it could it would be easy. A trained Gemologist is competent with a microscope.


Top
 Profile  
Reply with quote  
 Post subject: Re: How to identify natural amethyst vs heated amethyst
PostPosted: Mon Mar 23, 2020 1:14 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 20121
Location: San Francisco
And as an aside, vintage amethyst jewelry is not a guarantee of natural material. I have found synthetic amethyst in jewelry 35 years old.


Top
 Profile  
Reply with quote  
 Post subject: Re: How to identify natural amethyst vs heated amethyst
PostPosted: Tue Mar 24, 2020 9:00 pm 
Offline
Active Member

Joined: Mon Sep 03, 2012 11:32 am
Posts: 69
I guess with amethyst, most people dont bother to check wether its real or synthetic as its not that expensive than other semi precious stones and also not easy to detect aswell.


Top
 Profile  
Reply with quote  
 Post subject: Re: How to identify natural amethyst vs heated amethyst
PostPosted: Tue Mar 24, 2020 9:16 pm 
Offline
Gemology Online Veteran

Joined: Thu May 12, 2016 2:18 am
Posts: 739
14megapixel wrote:
I guess with amethyst, most people dont bother to check wether its real or synthetic as its not that expensive than other semi precious stones and also not easy to detect aswell.


Exactly .....


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 13 posts ] 

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