Amber Listserv / ""annealed" amber"

[Patty Rice]

I think the article by Dr. Gierlewski on the amberica west web site  
explains  the treatment of amber and is perhaps what was described by  
an American gemmologist as "annrealing."
I copy theimportant sectdion here: "current fashion demands clear  
stones with an intense colour: honey, cognac or various shades of red  
to crimson and cherry.
       This situation called for the construction of devices which  
would accelerate the natural processes of amber clarification and its  
obtaining of the desired colour. Such a device is the commonly used  
autoclave, a chamber stove filled with noble gas (argon or nitrogen)  
under considerable pressure. The pressure of the gas in the stove  
chamber during the heating rises from several dozen atmospheres to as  
much as 300 kg/cm2. Amber heated to a temperature above 200oC  
softens, while the gas bubbles it contains (which are the cause of  
the initial opacity) close up and the material becomes perfectly  
clear. Unfortunately, it also loses its true amber colour of  
saturated gold. It becomes almost colourless, only watery-greenish.  
In order to obtain the impression of intense colour it is necessary  
to perform an additional operation of roasting ready stones in normal  
atmosphere, so that they a thin colour layer on their surface obtain  
(as a result of oxidising). A third operation is also sometimes used  
to improve amber, or rather to adapt it to the customers' taste. It  
produces characteristic cracks, known as scales or, by the German  
term, "blitzes" i.e. flickers.     During the thermal operations  
described above, the amber becomes somewhat harder, less fissile and  
uniform in terms of transparency and colour. This makes it easier to  
establish standards when handling large batches of products in the  
wholesale trade."

www.ambericawest.com/gierlowski2.html

Patty C. Rice, Ph.D.
Author:Amber Golden Gem of the Ages
The most comprehensive book about amber in the USA!


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