Re: Irradiated gemstones

[Scott D Kniffin <Scott.D.Kniffin.1@gsfc.nasa.gov>]

Hi all, 

Actually, when you irradiate topaz it gets brown/dark purplish.  Then you
anneal it in an oven in some medium to slow the heat transfer (we used
sand) to get rid of the brown, leaving the blue.  The longer the
irradiation time, the darker the blue.  I did some as an experiment at UMD.
 My other half wears a pair that I had made into earrings for her.  The
trick while irradiating them with electrons is to flow enough water over
them to keep them cool (they actually shatter/explode if they get too hot)
but not so much that you shield them, thus driving up the irradiation time.
 Gamma's didn't work all that well if I remember correctly.  

A jeweller I knew told me that some were naturally irradiated, but I was
never able to confirm that. 

Scott Kniffin

RSO Unisys Federal Systems, Lanham, MD
CHO Radiation Effects Facility, GSFC, NASA
mailto:Scott.D.Kniffin.1@gsfc.nasa.gov

The opinions expressed here are my own. They do not necessarily represent
the views of Unisys or NASA.  This material has not been reviewed by my
manager or NASA.  

At 11:08 01/26/00 -0600, you wrote:
>>>are treated one paragraph read "All Blue Topazes presently in the market 
>>>were enhanced by irradiation and heating processes for color addition".
>>
>Shades/hues of blue can probably be manipulated by heat if the key element 
>is either copper or cobalt.
>
>Bjorn Cedervall  bcradsafers@hotmail.com

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html